An overlay GTK toolbar/widget

Question

I am writing a custom application in C using GTK+2.0 and Cairo. Just for learning purposes (and if successful, then for deployment), I wish to recreate something similar to a overlay toolbar/widget (I am sorry if the terminology is not correct) that appears when a mouse moves over a given area on the window, and disappears when the mouse moves away. The toolbar, as I imagine, should appear on top of the existing widgets without displacing them or altering the widget packing in any way. Is it possible to accomplish? If yes, can you please point me to relevant tutorials/examples and/or outline a way to do the same? Thanks in advance.

Answer 1

Not sure this is easily doable in GTK2. However, I learned recently that there's the GtkLayout widget which allows pixel exact rendering of widgets, so you can even display some widgets over others. Or you may implement your own container widget.

Please note that since GTK3, there's GtkOverlay which seem to do what you want.

You may also give a look to Clutter, which might allow this. Furthermore, there are projects of merging GTK and Clutter for GTK 4.

Answer 2

The little known GtkHandleBox is capable of doing what you want. I must warn you it is deprecated in GTK+3 because is going against the usual UI direction. Also, the correct positioning will be subject to the windows manager quirks, so I'd expect some issue in this regard.