A switchable-button% control displays and icon and a string label. It toggles between display of just the icon and a display with the label and the icon side-by-side.
label : string?
The callback is called when the button is pressed. The string and bitmap are used as discussed above.
If alternate-bitmap is supplied, then it is used when the button is switched to the view that just shows the bitmap. If it is not supplied, both modes show the same bitmap.
visible? : boolean?
Sets the visibility of the string part of the label.
Calls the button’s callback function.