mutter/HACKING

Don't commit substantive code in here without asking me,
hp@redhat.com.  Adding translations, no-brainer typo fixes, etc.  is
fine.

The script src/run-metacity.sh is useful to hack on the window manager. 
It runs metacity in an Xnest. e.g.:
 CLIENTS=3 ./run-metacity.sh
or 
 DEBUG=memprof ./run-metacity.sh
or whatever.

src/window.c is where all the guts of the window manager live. This is
basically the only remotely scary file.

src/frames.c is the GtkWidget that handles drawing window frames.

src/core.h defines the interface used by the GTK portion of the window
manager to talk to the other portions. There's some cruft in here
that's unused, since nearly all window operations have moved out of
this file so frameless apps can have window operations.

src/ui.h defines the interface the plain Xlib portion of the window
manager uses to talk to the GTK portion.

Files that include gdk.h or gtk.h are not supposed to include
display.h or window.h or other core files.

Files in the core (display.[hc], window.[hc]) are not supposed to
include gdk.h or gtk.h.

When hacking, remember that you can have multiple screens. The code is
also written to support multiple displays, but this is useless, since
you can just run two copies of the WM. Also, an XKillClient() or
shutdown on any display causes Xlib to exit the app, so it would be
broken. So the multi-display thing is mostly just for code
cleanliness.  Multi-screen on the other hand is important for some
people.

Remember that strings stored in X properties are not in UTF-8, and
they have to end up in UTF-8 before we try putting them through Pango.

If you make any X request involving a client window, you have to
meta_error_trap_push() around the call; this is not necessary for 
X requests on the frame windows.

Remember that not all windows have frames, and window->frame can 
be NULL.

The code could use cleanup in a lot of places, feel free to do so.