I've been trying really hard to create a window with no decoration and a transparent background using PyGTK. I would then draw the content of the window with Cairo. But I can't get it to work.

I've tried a lot of different ways, they all failed, this is one of them

#!/usr/bin/env pythonimport pygtk
pygtk.require('2.0')
import gtk, sys, cairowin = Nonedef expose (widget, event):cr = widget.window.cairo_create()#Start drawingcr.set_operator(cairo.OPERATOR_CLEAR)cr.set_source_rgba(0.5,1.0,0.0,0.5)cr.rectangle(0, 0, 0.9, 0.8)cr.fill()def main (argc):global winwin = gtk.Window()win.set_decorated(False)win.connect('delete_event', gtk.main_quit)win.connect('expose-event', expose)win.set_app_paintable(True)win.show()gtk.main()if __name__ == '__main__':sys.exit(main(sys.argv))

So, what is the simplest way to do this?

So, I actually figured this out myself.

This is a working example. I've commented the relevant parts just in case somebody else is interested in how to do this.

#!/usr/bin/env pythonimport pygtk
pygtk.require('2.0')
import gtk, sys, cairo
from math import pidef expose (widget, event):cr = widget.window.cairo_create()# Sets the operator to clear which deletes everything below where an object is drawncr.set_operator(cairo.OPERATOR_CLEAR)# Makes the mask fill the entire windowcr.rectangle(0.0, 0.0, *widget.get_size())# Deletes everything in the window (since the compositing operator is clear and mask fills the entire windowcr.fill()# Set the compositing operator back to the defaultcr.set_operator(cairo.OPERATOR_OVER)# Draw a fancy little circle for demonstration purposecr.set_source_rgba(0.5,1.0,0.0,1)cr.arc(widget.get_size()[0]/2,widget.get_size()[1]/2,widget.get_size()[0]/2,0,pi*2)cr.fill()def main (argc):win = gtk.Window()win.set_decorated(False)# Makes the window paintable, so we can draw directly on itwin.set_app_paintable(True)win.set_size_request(100, 100)# This sets the windows colormap, so it supports transparency.# This will only work if the wm support alpha channelscreen = win.get_screen()rgba = screen.get_rgba_colormap()win.set_colormap(rgba)win.connect('expose-event', expose)win.show()