Warning
gtk_window_set_opacity has been deprecated since version 3.8 and should not be used in newly-written code. Use gtk_widget_set_opacity instead.
Request the windowing system to make window partially transparent,
with opacity 0 being fully transparent and 1 fully opaque. (Values
of the opacity parameter are clamped to the [0,1] range.) On X11
this has any effect only on X screens with a compositing manager
running. See gtk_widget_is_composited(). On Windows it should work
always.
Note that setting a window's opacity after the window has been
shown causes it to flicker once on Windows.
Since 2.12
Warning gtk_window_set_opacity has been deprecated since version 3.8 and should not be used in newly-written code. Use gtk_widget_set_opacity instead. Request the windowing system to make window partially transparent, with opacity 0 being fully transparent and 1 fully opaque. (Values of the opacity parameter are clamped to the [0,1] range.) On X11 this has any effect only on X screens with a compositing manager running. See gtk_widget_is_composited(). On Windows it should work always. Note that setting a window's opacity after the window has been shown causes it to flicker once on Windows. Since 2.12