fb.taskbar Windows Taskbar

fb.taskbar controls the main window's taskbar button: thumbnail-toolbar buttons, progress, the overlay icon and flashing. Called from a Default UI or Columns UI panel, every method fails with PANEL_MODE_UNSUPPORTED.

flash(options?)

Signature: fb.taskbar.flash(options?: TaskbarFlashParams): Promise<TaskbarFlashResponse>

Parameter	Type	Required	Description
options.count	number	No	Number of flashes. Defaults to 3
options.interval	number	No	Milliseconds between flashes; omitted or 0 uses the system cursor blink rate

Flashes the main window's taskbar button. Fails with OPERATION_FAILED when that button has not been created yet or the main window no longer exists.

const result = await fb.taskbar.flash({ count: 3 });

setOverlayIcon(options?)

Signature: fb.taskbar.setOverlayIcon(options?: TaskbarSetOverlayIconParams): Promise<TaskbarSetOverlayIconResponse>

Parameter	Type	Required	Description
options.icon	string | null	No	Raw Base64-encoded .ico file bytes; no data: or base64: prefix. Omit or pass null to clear the overlay
options.description	string	No	Accessible icon description

Lays a small icon over the taskbar button, typically to show the playback state; calling it without arguments clears the overlay. Fails with OPERATION_FAILED when the taskbar button does not exist yet or the system rejects the call.

// Raw Base64 .ico bytes the theme stored earlier; null clears the overlay
const icon = localStorage.getItem('pausedOverlayIcon');
const result = await fb.taskbar.setOverlayIcon({ icon, description: 'Paused' });

setThumbnailButtons(buttons)

Signature: fb.taskbar.setThumbnailButtons(buttons: ThumbnailButton[]): Promise<TaskbarSetThumbnailButtonsResponse>

Parameter	Type	Required	Description
buttons	ThumbnailButton[]	Yes	Up to seven buttons with id, tooltip, optional icon, and optional state flags

Every button icon uses raw Base64-encoded .ico file bytes. PNG, JPEG, SVG, Data URLs, and the file.write-specific base64: marker are not accepted icon representations. Invalid values may fall back to a default icon.

Installs the thumbnail toolbar once for the window. Use updateButton(options) for later state changes; it cannot add or remove buttons. Button clicks emit taskbar:buttonClicked with { id }. setProgress({ state, value? }) accepts none, indeterminate, normal, error, or paused; value is a 0-1 fraction for determinate states.

const result = await fb.taskbar.setThumbnailButtons([
    { id: 'play-pause', tooltip: 'Play or pause' }
]);

Update an existing thumbnail-toolbar button without reinstalling the toolbar:

await fb.taskbar.updateButton({ id: 'play', tooltip: 'Pause', enabled: true });