Is it possible to theme GUI applications with custom Python window manager?

Question

I'm trying to create a simple custom window manager in Python using xlib (based on Whimsy and PLWM).

Is it possible to skin the default look of GUI applications, e.g. the default scroll bars or buttons, using just xlib? Or does this need to be done separately for each application? Or is it something else entirely?

Thanks

Answer 1

No, xlib has no notion of scroll bars or buttons. Highest level objects are windows / drawables - you can listen for events and draw on top of windows. Everything else is implemented on top of core X protocol in user code

Answer 2

The default behaviour comes from the Windows Manager and it dictates the look and colors of all the default widgets as some GUI libraries call them. These are pre-define within the Windows Manager's code or XML configration files. Check the source-code of Whimsy.

You can customize the look of many things inside your own application, but it won't affect the rest of the scrollbars for instance.

There are also some default behaviors of the X-server that you have to take into account.