com.smartgwt.client.widgets.tab

Class Tab

java.lang.Object

com.smartgwt.client.core.JsObject

com.smartgwt.client.core.DataClass

com.smartgwt.client.core.RefDataClass

com.smartgwt.client.widgets.tab.Tab

All Implemented Interfaces:

com.google.gwt.event.shared.HasHandlers, HasTabDeselectedHandlers, HasTabSelectedHandlers

public class Tab
extends RefDataClass
implements HasTabDeselectedHandlers, HasTabSelectedHandlers

Tab instances for use with TabSet. Tab instances specify the appearance (setTitle, setIcon) of the tab, and provide the tab's pane. See setTabs for further details.

Field Summary

Fields inherited from class com.smartgwt.client.core.RefDataClass

id

Fields inherited from class com.smartgwt.client.core.DataClass

factoryCreated, factoryProperties

Fields inherited from class com.smartgwt.client.core.JsObject

jsObj

Constructor Summary

Constructors

Constructor and Description
Tab()
Tab(com.google.gwt.core.client.JavaScriptObject jsObj)
Tab(java.lang.String title)
Tab(java.lang.String title, java.lang.String icon)

Method Summary

Modifier and Type	Method and Description
com.google.gwt.event.shared.HandlerRegistration	addTabDeselectedHandler(TabDeselectedHandler handler) Add a tabDeselected handler.
com.google.gwt.event.shared.HandlerRegistration	addTabSelectedHandler(TabSelectedHandler handler) Add a tabSelected handler.
java.lang.Boolean	getCanAdaptWidth() If enabled, the tab will collapse to show just its icon when showing the title would cause overflow of a containing TabBar.
java.lang.Boolean	getCanClose() Determines whether this tab should show a close icon allowing the user to dismiss the tab by clicking on the close icon directly.
java.lang.Boolean	getCanEditTitle() If specified, overrides the TabSet.canEditTabTitles setting, for this one tab only.
java.lang.Boolean	getCanReorder() If TabSet.canReorderTabs is set to true, setting canReorder explicitly to false for some tab will disallow drag-reordering of this tab.
java.lang.String	getCloseIcon() Custom src for the close icon for this tab to display if it is closeable.
java.lang.Integer	getCloseIconSize() Size of the closeIcon for this tab.
Menu	getContextMenu() Context menu to show for this object, an instance of the Menu widget.
java.lang.Boolean	getDisabled() If specified, this tab will initially be rendered in a disabled state.
AdvancedCriteria	getEnableWhen() Criteria to be evaluated to determine whether this Tab should be enabled.
java.lang.String	getIcon() If specified, this tab will show an icon next to the tab title.
java.lang.Integer	getIconHeight() If icon is specified, this property may be used to specify a height for the icon.
java.lang.Integer	getIconSize() If icon is specified, this property may be used to specify a size for the icon.
java.lang.Integer	getIconWidth() If icon is specified, this property may be used to specify a width for the icon.
java.lang.String	getID() Optional ID for the tab, which can later be used to reference the tab.
java.lang.String	getName() Optional name for the tab, which can later be used to reference the tab.
static Tab	getOrCreateRef(com.google.gwt.core.client.JavaScriptObject jsObj)
Canvas	getPane() Specifies the pane associated with this tab.
java.lang.Integer	getPaneMargin() Space to leave around the pane within this Tab.
java.lang.String	getPickerTitle() If TabSet.showTabPicker is true for this TabSet, if set this property will determine the title of the picker menu item for this tab.
java.lang.String	getPrompt() Specifies the prompt to be displayed when the mouse hovers over the tab.
StatefulCanvas	getTabCanvas() Returns the live Canvas used to represent this tab in a tabSet.
TabSet	getTabSet()
java.lang.String	getTitle() Specifies the title of the this tab.
java.lang.String	getTitleStyle() A separate style for the title text.
int	getWidth() You can specify an explicit width for the tab using this property.
void	setCanAdaptWidth(java.lang.Boolean canAdaptWidth) If enabled, the tab will collapse to show just its icon when showing the title would cause overflow of a containing TabBar.
void	setCanClose(boolean canClose) See setCanClose().
void	setCanClose(java.lang.Boolean canClose) Determines whether this tab should show a close icon allowing the user to dismiss the tab by clicking on the close icon directly.
void	setCanEditTitle(java.lang.Boolean canEditTitle) If specified, overrides the TabSet.canEditTabTitles setting, for this one tab only.
void	setCanReorder(java.lang.Boolean canReorder) If TabSet.canReorderTabs is set to true, setting canReorder explicitly to false for some tab will disallow drag-reordering of this tab.
void	setCloseIcon(java.lang.String closeIcon) Custom src for the close icon for this tab to display if it is closeable.
void	setCloseIconSize(java.lang.Integer closeIconSize) Size of the closeIcon for this tab.
void	setContextMenu(Menu contextMenu) Context menu to show for this tab.
void	setDisabled(boolean disabled) If specified, this tab will initially be rendered in a disabled state.
void	setEnableWhen(AdvancedCriteria enableWhen) Criteria to be evaluated to determine whether this Tab should be enabled.
void	setIcon(java.lang.String icon) If specified, this tab will show an icon next to the tab title.
void	setIcon(java.lang.String icon, int iconSize) If specified, this tab will show an icon next to the tab title.
void	setIcon(java.lang.String icon, int iconWidth, int iconHeight) If specified, this tab will show an icon next to the tab title.
void	setIconHeight(java.lang.Integer iconHeight) If icon is specified, this property may be used to specify a height for the icon.
void	setIconSize(java.lang.Integer iconSize) If icon is specified, this property may be used to specify a size for the icon.
void	setIconWidth(java.lang.Integer iconWidth) If icon is specified, this property may be used to specify a width for the icon.
void	setID(java.lang.String ID) Optional ID for the tab, which can later be used to reference the tab.
void	setName(java.lang.String name) Optional name for the tab, which can later be used to reference the tab.
void	setPane(Canvas pane) Specifies the pane associated with this tab.
void	setPaneID(java.lang.String paneID)
void	setPaneMargin(java.lang.Integer paneMargin) Space to leave around the pane within this Tab.
void	setPickerTitle(java.lang.String pickerTitle) If TabSet.showTabPicker is true for this TabSet, if set this property will determine the title of the picker menu item for this tab.
void	setPrompt(java.lang.String prompt) Specifies the prompt to be displayed when the mouse hovers over the tab.
void	setTabSet(TabSet tabSet)
void	setTitle(java.lang.String title) Specifies the title of the this tab.
void	setTitleStyle(java.lang.String titleStyle) Provide a separate style for the title text.
void	setWidth(int width) You can specify an explicit width for the tab using this property.

Methods inherited from class com.smartgwt.client.core.RefDataClass

getRef, getRef, internalSetID

Methods inherited from class com.smartgwt.client.core.DataClass

applyFactoryProperties, doAddHandler, fireEvent, getAttribute, getAttributeAsBoolean, getAttributeAsBoolean, getAttributeAsDate, getAttributeAsDouble, getAttributeAsDoubleArray, getAttributeAsFloat, getAttributeAsInt, getAttributeAsIntArray, getAttributeAsJavaScriptObject, getAttributeAsLong, getAttributeAsMap, getAttributeAsObject, getAttributeAsRecord, getAttributeAsString, getAttributeAsStringArray, getAttributes, getHandlerCount, isFactoryCreated, setAttribute, setAttribute, setAttribute, setAttribute, setAttribute, setAttribute, setAttribute, setAttribute, setAttribute, setAttribute, setAttribute, setAttribute, setAttribute, setAttribute, setAttribute, setAttribute, setAttribute, setAttribute, setAttribute, setAttribute, setAttribute, setAttribute, setAttribute, setAttribute, setAttributeAsJavaObject, setFactoryCreated

Methods inherited from class com.smartgwt.client.core.JsObject

equals, getJsObj, hashCode, isCreated, setJavaScriptObject, setJsObj

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, toString, wait, wait, wait

Methods inherited from interface com.google.gwt.event.shared.HasHandlers

fireEvent

Constructor Detail

Tab

public Tab()

Tab

public Tab(com.google.gwt.core.client.JavaScriptObject jsObj)

Tab

public Tab(java.lang.String title)

Tab

public Tab(java.lang.String title,
           java.lang.String icon)

Method Detail

getOrCreateRef

public static Tab getOrCreateRef(com.google.gwt.core.client.JavaScriptObject jsObj)

setCanAdaptWidth

public void setCanAdaptWidth(java.lang.Boolean canAdaptWidth)

If enabled, the tab will collapse to show just its icon when showing the title would cause overflow of a containing TabBar.

Parameters:

canAdaptWidth - New canAdaptWidth value. Default value is false

See Also:

Button.setCanAdaptWidth(java.lang.Boolean), Canvas.setCanAdaptWidth(java.lang.Boolean)

getCanAdaptWidth

public java.lang.Boolean getCanAdaptWidth()

If enabled, the tab will collapse to show just its icon when showing the title would cause overflow of a containing TabBar.

Returns:

Current canAdaptWidth value. Default value is false

See Also:

Button.getCanAdaptWidth(), Canvas.getCanAdaptWidth()

getCanClose

public java.lang.Boolean getCanClose()

Determines whether this tab should show a close icon allowing the user to dismiss the tab by clicking on the close icon directly. The URL for the close icon's image will be derived from TabSet.closeTabIcon by default, but may be overridden by explicitly specifying closeIcon.

If unset or null, this property is derived from TabSet.canCloseTabs.

Note that setting canClose means that icon cannot be used, because it's used for the closeIcon - see TabSet.canCloseTabs for a workaround.

Returns:

Current canClose value. Default value is null

See Also:

com.smartgwt.client.widgets.tab.TabSet#closeClick, Closeable Tabs Example

getCanEditTitle

public java.lang.Boolean getCanEditTitle()

If specified, overrides the TabSet.canEditTabTitles setting, for this one tab only.

Note that the TabSet's titleEditEvent must be set to a supported TabTitleEditEvent in order for users to be able to edit this tab's title.

Returns:

Current canEditTitle value. Default value is null

See Also:

TabSet.getCanEditTabTitles(), User-Editable Titles Example

setCanReorder

public void setCanReorder(java.lang.Boolean canReorder)

If TabSet.canReorderTabs is set to true, setting canReorder explicitly to false for some tab will disallow drag-reordering of this tab. Has no effect if canReorderTabs is not true at the tabSet level.

Note that this setting also disallows a reorder of another tab into the slot before or following this tab. This means for tabs located at the beginning or end of the tab-bar, users cannot changing the index of the tab by dropping another before or after it. However if you have a canReorder:false tab which is not at the beginning or end of the tab bar, users can drag reorder other tabs around it which may ultimately change its position.

Parameters:

canReorder - New canReorder value. Default value is null

See Also:

TabSet.setCanReorderTabs(java.lang.Boolean)

getCanReorder

public java.lang.Boolean getCanReorder()

If TabSet.canReorderTabs is set to true, setting canReorder explicitly to false for some tab will disallow drag-reordering of this tab. Has no effect if canReorderTabs is not true at the tabSet level.

Note that this setting also disallows a reorder of another tab into the slot before or following this tab. This means for tabs located at the beginning or end of the tab-bar, users cannot changing the index of the tab by dropping another before or after it. However if you have a canReorder:false tab which is not at the beginning or end of the tab bar, users can drag reorder other tabs around it which may ultimately change its position.

Returns:

Current canReorder value. Default value is null

See Also:

TabSet.getCanReorderTabs()

getCloseIcon

public java.lang.String getCloseIcon()

Custom src for the close icon for this tab to display if it is closeable. See canClose and TabSet.canCloseTabs.

Returns:

Current closeIcon value. Default value is null

See Also:

SCImgURL

getCloseIconSize

public java.lang.Integer getCloseIconSize()

Size of the closeIcon for this tab. If unspecified the icon will be sized according to TabSet.closeTabIconSize

Returns:

Current closeIconSize value. Default value is null

getDisabled

public java.lang.Boolean getDisabled()

If specified, this tab will initially be rendered in a disabled state. methods.

Returns:

Current disabled value. Default value is null

setEnableWhen

public void setEnableWhen(AdvancedCriteria enableWhen)

Criteria to be evaluated to determine whether this Tab should be enabled. Re-evaluated whenever data in the tab.ruleScope changes.

It works the same as Canvas.enableWhen

Parameters:

enableWhen - New enableWhen value. Default value is null

See Also:

RuleCriteria overview and related methods

getEnableWhen

public AdvancedCriteria getEnableWhen()

Criteria to be evaluated to determine whether this Tab should be enabled. Re-evaluated whenever data in the tab.ruleScope changes.

It works the same as Canvas.enableWhen

Returns:

Current enableWhen value. Default value is null

See Also:

RuleCriteria overview and related methods

getIcon

public java.lang.String getIcon()

If specified, this tab will show an icon next to the tab title.

NOTE: if you enable closeable tabs, tab.icon is used for the close icon. TabSet.canCloseTabs describes a workaround to enable both a closeIcon and a second icon to be shown.

Use TabSet.tabIconClick() to add an event handler specifically for clicks on the icon.

If a tab becomes disabled, a different icon will be loaded by adding a suffix to the image name (see Button.icon).

You should specify a size for the icon via iconSize or iconWidth and iconHeight. Without an explicitly specified size, tabs may be drawn overlapping or with gaps the first time a page is loaded, because the icon is not cached and therefore its size isn't known.

Returns:

Current icon value. Default value is null

See Also:

TabClickEvent, SCImgURL, Orientation Example

getIconHeight

public java.lang.Integer getIconHeight()

If icon is specified, this property may be used to specify a height for the icon.

Returns:

Current iconHeight value. Default value is null

getIconSize

public java.lang.Integer getIconSize()

If icon is specified, this property may be used to specify a size for the icon. Per side sizing may be specified instead via iconWidth and iconHeight.

Returns:

Current iconSize value. Default value is 16

getIconWidth

public java.lang.Integer getIconWidth()

If icon is specified, this property may be used to specify a width for the icon.

Returns:

Current iconWidth value. Default value is null

setName

public void setName(java.lang.String name)

Optional name for the tab, which can later be used to reference the tab. APIs requiring a reference to a tab will accept the tab's name [including TabSet.selectTab(), TabSet.updateTab(), TabSet.removeTab()].
This name will also be passed to the TabSet.tabSelected() and TabSet.tabDeselected() handler functions, if specified.

This identifier is requred to be locally unique to the TabSet and cannot be used to get a global reference to the Tab. If you want a global reference, set ID instead.

Parameters:

name - New name value. Default value is null

See Also:

TabName

getName

public java.lang.String getName()

Optional name for the tab, which can later be used to reference the tab. APIs requiring a reference to a tab will accept the tab's name [including TabSet.selectTab(), TabSet.updateTab(), TabSet.removeTab()].
This name will also be passed to the TabSet.tabSelected() and TabSet.tabDeselected() handler functions, if specified.

This identifier is requred to be locally unique to the TabSet and cannot be used to get a global reference to the Tab. If you want a global reference, set ID instead.

Returns:

Current name value. Default value is null

See Also:

TabName

getPane

public Canvas getPane()

Specifies the pane associated with this tab. You have two options for the value of the pane attribute:

• ID - The global ID of an already created Canvas (or subclass).
• Canvas - A live instance of a Canvas (or subclass).

Returns:

Current pane value. Default value is null

See Also:

TabSet.updateTab(int, com.smartgwt.client.widgets.Canvas)

setPaneMargin

public void setPaneMargin(java.lang.Integer paneMargin)

Space to leave around the pane within this Tab. If specified, this property takes precedence over TabSet.paneMargin

Parameters:

paneMargin - New paneMargin value. Default value is null

getPaneMargin

public java.lang.Integer getPaneMargin()

Space to leave around the pane within this Tab. If specified, this property takes precedence over TabSet.paneMargin

Returns:

Current paneMargin value. Default value is null

getPickerTitle

public java.lang.String getPickerTitle()

If TabSet.showTabPicker is true for this TabSet, if set this property will determine the title of the picker menu item for this tab. If unset, title will be used instead.

Returns:

Current pickerTitle value. Default value is null

See Also:

TabSet.getShowTabPicker(), getTitle(), HTMLString

getPrompt

public java.lang.String getPrompt()

Specifies the prompt to be displayed when the mouse hovers over the tab.

Returns:

Current prompt value. Default value is null

See Also:

HTMLString

getTitle

public java.lang.String getTitle()

Specifies the title of the this tab.

Returns:

Current title value. Default value is null

See Also:

TabSet.setTabTitle(int, java.lang.String), HTMLString

getWidth

public int getWidth()

You can specify an explicit width for the tab using this property. Note that tabs automatically size to make room for the full title, but if you want to e.g. specify a uniform width for all tabs in a TabSet, this property enables you to do so.

Returns:

Current width value. Default value is 100

addTabDeselectedHandler

public com.google.gwt.event.shared.HandlerRegistration addTabDeselectedHandler(TabDeselectedHandler handler)

Add a tabDeselected handler.

Optional handler to fire when a tab is deselected. Calling TabDeselectedEvent.cancel will cancel the new selection, leaving this tab selected. As with TabSet.tabSelected() this method only fires when the tabset is drawn.

Specified by:

addTabDeselectedHandler in interface HasTabDeselectedHandlers

Parameters:

handler - the tabDeselected handler

Returns:

HandlerRegistration used to remove this handler

addTabSelectedHandler

public com.google.gwt.event.shared.HandlerRegistration addTabSelectedHandler(TabSelectedHandler handler)

Add a tabSelected handler.

Optional handler to fire when a tab is selected. As with TabSet.tabSelected() this method only fires when the tabset is drawn.

Specified by:

addTabSelectedHandler in interface HasTabSelectedHandlers

Parameters:

handler - the tabSelected handler

Returns:

HandlerRegistration used to remove this handler

setID

public void setID(java.lang.String ID)

Optional ID for the tab, which can later be used to reference the tab. APIs requiring a reference to a tab will accept the tabs ID [including TabSet.selectTab, TabSet.updateTab, TabSet.removeTab].
The ID will also be passed to the TabSet.tabSelected and TabSet.tabDeselected handler functions, if specified.

Note that if you provide an ID, it must be globally unique.

Parameters:

ID - ID Default value is null

getID

public java.lang.String getID()

Optional ID for the tab, which can later be used to reference the tab. APIs requiring a reference to a tab will accept the tabs ID [including TabSet.selectTab, TabSet.updateTab, TabSet.removeTab].
The ID will also be passed to the TabSet.tabSelected and TabSet.tabDeselected handler functions, if specified.

Note that if you provide an ID, it must be globally unique.

Returns:

String

setTitle

public void setTitle(java.lang.String title)

Specifies the title of the this tab. To change the title after the TabSet has been created, call TabSet.setTabTitle.

Parameters:

title - title Default value is null

setDisabled

public void setDisabled(boolean disabled)

If specified, this tab will initially be rendered in a disabled state.

Parameters:

disabled - disabled Default value is null

setIcon

public void setIcon(java.lang.String icon)

If specified, this tab will show an icon next to the tab title. Note that as with icon, the URL of a tabs icon will be updated to reflect disabled state.
If desired a click handler may be assigned to the icon, which will be fired when the user clicks the tab. This method takes a single parameter tab, a pointer to the tab object.

Parameters:

icon - icon Default value is null

See Also:

Orientation Example

setIcon

public void setIcon(java.lang.String icon,
                    int iconWidth,
                    int iconHeight)

If specified, this tab will show an icon next to the tab title. Note that as with icon, the URL of a tabs icon will be updated to reflect disabled state.
If desired a click handler may be assigned to the icon, which will be fired when the user clicks the tab. This method takes a single parameter tab, a pointer to the tab object.

Parameters:

icon - icon Default value is null

iconWidth - the icon width

iconHeight - the icon height

See Also:

Orientation Example

setIcon

public void setIcon(java.lang.String icon,
                    int iconSize)

If specified, this tab will show an icon next to the tab title. Note that as with icon, the URL of a tabs icon will be updated to reflect disabled state.
If desired a click handler may be assigned to the icon, which will be fired when the user clicks the tab. This method takes a single parameter tab, a pointer to the tab object.

Parameters:

icon - icon Default value is null

iconSize - the icon size

See Also:

Orientation Example

setIconSize

public void setIconSize(java.lang.Integer iconSize)

If icon is specified, this property may be used to specify a size for the icon. Per side sizing may be specified instead via iconWidth and iconHeight.

Parameters:

iconSize - New iconSize value. Default value is 16

setIconWidth

public void setIconWidth(java.lang.Integer iconWidth)

If icon is specified, this property may be used to specify a width for the icon.

Parameters:

iconWidth - New iconWidth value. Default value is null

setIconHeight

public void setIconHeight(java.lang.Integer iconHeight)

If icon is specified, this property may be used to specify a height for the icon.

Parameters:

iconHeight - New iconHeight value. Default value is null

setPickerTitle

public void setPickerTitle(java.lang.String pickerTitle)

If TabSet.showTabPicker is true for this TabSet, if set this property will determine the title of the picker menu item for this tab. If unset, title will be used instead

Parameters:

pickerTitle - New pickerTitle value. Default value is null

See Also:

TabSet.setShowTabPicker(java.lang.Boolean), setTitle(java.lang.String), HTMLString

setWidth

public void setWidth(int width)

You can specify an explicit width for the tab using this property. Note that tabs automatically size to make room for the full title, but if you want to e.g. specify a uniform width for all tabs in a TabSet, this property enables you to do so.

Parameters:

width - New width value. Default value is 100

setPrompt

public void setPrompt(java.lang.String prompt)

Specifies the prompt to be displayed when the mouse hovers over the tab.

Parameters:

prompt - New prompt value. Default value is null

See Also:

HTMLString

setCanEditTitle

public void setCanEditTitle(java.lang.Boolean canEditTitle)

If specified, overrides the TabSet.canEditTabTitles setting, for this one tab only.

Note that the TabSet's titleEditEvent must be set to a supported TabTitleEditEvent in order for users to be able to edit this tab's title.

Parameters:

canEditTitle - New canEditTitle value. Default value is null

See Also:

TabSet.setCanEditTabTitles(java.lang.Boolean), User-Editable Titles Example

setCanClose

public void setCanClose(java.lang.Boolean canClose)

Determines whether this tab should show a close icon allowing the user to dismiss the tab by clicking on the close icon directly. The URL for the close icon's image will be{M{ derived from TabSet.closeTabIcon by default, but may be overridden by explicitly specifying closeIcon.

If unset or null, this property is derived from TabSet.canCloseTabs.

Note that setting canClose means that icon cannot be used, because it's used for the closeIcon - see TabSet.canCloseTabs for a workaround.

Parameters:

canClose - New canClose value. Default value is null

See Also:

com.smartgwt.client.widgets.tab.TabSet#closeClick, Closeable Tabs Example

setCanClose

public void setCanClose(boolean canClose)

See setCanClose().

Parameters:

canClose - New canClose value.

setCloseIcon

public void setCloseIcon(java.lang.String closeIcon)

Custom src for the close icon for this tab to display if it is closeable. See canClose and TabSet.canCloseTabs.

Parameters:

closeIcon - New closeIcon value. Default value is null

See Also:

SCImgURL

setCloseIconSize

public void setCloseIconSize(java.lang.Integer closeIconSize)

Size of the closeIcon for this tab. If unspecified the icon will be sized according to TabSet.closeTabIconSize

Parameters:

closeIconSize - New closeIconSize value. Default value is null

setPaneID

public void setPaneID(java.lang.String paneID)

setTitleStyle

public void setTitleStyle(java.lang.String titleStyle)

Provide a separate style for the title text. If set and the ImgTab is vertical, a "v" will be automatically prepended to the style name (hence "tabTitle" -> "vtabTitle").

Parameters:

titleStyle - the title style

getTitleStyle

public java.lang.String getTitleStyle()

A separate style for the title text. If set and the ImgTab is vertical, a "v" will be automatically prepended to the style name (hence "tabTitle" -> "vtabTitle").

Returns:

the title style

setPane

public void setPane(Canvas pane)

Specifies the pane associated with this tab. You can change the pane associated with a given tab after the TabSet has been created by calling TabSet.updateTab(int, com.smartgwt.client.widgets.Canvas)

Parameters:

pane - the tab pane

setContextMenu

public void setContextMenu(Menu contextMenu)

Context menu to show for this tab.

Parameters:

contextMenu - contextMenu Default value is null

getContextMenu

public Menu getContextMenu()

Context menu to show for this object, an instance of the Menu widget.

Returns:

Menu

getTabSet

public TabSet getTabSet()

setTabSet

public void setTabSet(TabSet tabSet)

getTabCanvas

public StatefulCanvas getTabCanvas()

Returns the live Canvas used to represent this tab in a tabSet. Will return null if this Tab has not been added to a TabSet or if the tabset is not yet drawn.

The underlying SmartClient class of the returned canvas depends on #getUseSimpleTabs. If this property is false, the returned canvas will be a ImgTab instance. If true the canvas will be a com.smartgwt.client.widgets.tab.Button instance. Note that you can make use of ImgTab APIs by using the getJsObj() and create() APIs to "cast" to the appropriate type - for example:
ImgTab liveTab = ImgTab.create(myTabSet.getTabCanvas(2).getJsObj());

Returns:

live Canvas for this tab in a tabSet.