Comment 1 for bug 341787

As the sugar.tutorius.overlayer is currently implemented, it would be a matter of creating a widget similar to the overlayer.TextBubble but with a mask to capture events such as mouse clicks and setting its event mask to the non-interesting region. see http://pygtk.org/pygtk2reference/class-gtkwidget.html#method-gtkwidget--input-shape-combine-mask. How the "mask" is actually drawn could be with cairo.fill() with an alpha of, say 0.5f.