[dev] [dwm] adding WM_WINDOW_ROLE rule

Hello dear dwm users,

There is something that make me sad with dwm, there is a lack of role
rules for clients. I explain : clients have instance and name using
WM_CLASS, but there is also WM_WINDOW_ROLE which is really important
and useful.

Example : you want your firefox window tiled but not the download
manager or not the preference client you could make a rule that catch
the WM_WINDOW_ROLE

-> xprop WM_WINDOW_ROLE on the firefox windows and sub-windows
--> xprop WM_WINDOW_ROLE
--> WM_WINDOW_ROLE(STRING) = "Preferences" # this is preferences
--> xprop WM_WINDOW_ROLE
--> WM_WINDOW_ROLE(STRING) = "browser" # the main window
--> xprop WM_WINDOW_ROLE
--> WM_WINDOW_ROLE(STRING) = "Manager" # the download window

Why is this so important? Because you can make more rules to specifig
windows, I personally like to have the main browser window tiled but
not the download window. This is also the same thing with pidgin,
pidgin has a conversation window and a buddy list that have differents
WM_WINDOW_ROLE.

Of coure we could use the `title' rules but it's different on each
locale you are using so it sucks as well.

I would like to write a patch but for the moment I don't find the good
function that handle WM_WINDOW_ROLE.

With kind regards.

-- 
Demelier David