Gets/sets whether or not the preview is marked active (selected) in the taskbar.
The controller for this preview. A controller is required to provide the behavior and appearance of the taskbar previews. It is responsible for determining the size and contents of the preview, which buttons are displayed and how the application responds to user actions on the preview.
Neither preview makes full use of the controller. See the documentation for nsITaskbarWindowPreview and nsITaskbarTabPreview for details on which controller methods are used.
The controller is not allowed to be null.
nsITaskbarPreviewController
Enables/disables custom drawing of thumbnails and previews
Default value: false
The tooltip displayed above the preview when the user hovers over it
Default: an empty string
Whether or not the preview is visible.
Changing this option is expensive for tab previews since toggling this option will destroy/create the proxy window and its registration with the taskbar. If any step of that fails, an exception will be thrown.
For window previews, this operation is very cheap.
Default: false
Optional aInstancePtr: objectA run time mechanism for interface discovery.
NS_OK if the interface is supported by the associated instance, NS_NOINTERFACE if it is not.
aInstancePtr must not be null.
[in] A requested interface IID
[out] A pointer to an interface pointer to receive the result.
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nsITaskbarWindowPreview
This interface represents the preview for a window in the taskbar. By default, Windows implements much of the behavior for applications by default. The primary purpose of this interface is to allow Gecko applications to take control over parts of the preview. Some parts are not controlled through this interface: the title and icon of the preview match the title and icon of the window always.
By default, Windows takes care of drawing the thumbnail and preview for the application however if enableCustomDrawing is set to true, then the controller will start to receive requestPreview and requestThumbnail calls as well as reads on the thumbnailAspectRatio, width and height properties.
By default, nsITaskbarWindowPreviews are visible. When made invisible, the window disappears from the list of windows in the taskbar for the application.
If the window has any visible nsITaskbarTabPreviews, then the nsITaskbarWindowPreview for the corresponding window is automatically hidden. This is not reflected in the visible property. Note that other parts of the system (such as alt-tab) may still request thumbnails and/or previews through the nsITaskbarWindowPreview's controller.
nsITaskbarWindowPreview will never invoke the controller's onClose or onActivate methods since handling them may conflict with other internal Gecko state and there is existing infrastructure in place to allow clients to handle those events
Window previews may have a toolbar with up to 7 buttons. See nsITaskbarPreviewButton for more information about button properties.