New flag to ignore user input

[Сергей Болотов]

Hello everyone,

Our team has encountered situation in which window manager should 
ignore all the user input for specific window. Such behaviour, similar 
to win32 WS_DISABLED window style, needed, for example, when application 
has many windows, one of which is showing modal message which requires 
attention. The problem we faced is that if one of non-parent application 
windows has _NET_WM_STATE_ABOVE, or even worse - 
_NET_WM_STATE_FULLSCREEN flag of _NET_WM_STATE property, it will cover 
modal window, thus not allowing user to continue work with app. We 
consider adding new flag to the specification which will show WM that 
window is disabled, thus preventing it from receiving user input, 
changing its place in stacking order, activation and other manipulation 
by WM. It may be an additional flag of _NET_WM_STATE property, named, 
for example _NET_WM_STATE_DISABLED, and could be handled like this (in 
xfwm4):

@@ handleButtonPress (DisplayInfo *display_info, XButtonEvent * ev)
      client = myDisplayGetClientFromWindow (display_info, ev->window, 
SEARCH_FRAME | SEARCH_WINDOW);
      if (client)
      {
+        XWMState wmState;
          state = ev->state & MODIFIER_MASK;
          win = ev->subwindow;
          screen_info = client->screen_info;
+
+        XGetWMState(display, client->window, &wmState);
+        if(wmState.state & NET_WM_STATE_DISABLED)
+        {
+            /* Release pending events */
+            XAllowEvents (display_info->dpy, replay ? ReplayPointer : 
SyncPointer, CurrentTime);
+
+            return EVENT_FILTER_REMOVE;
+        }

          if ((ev->button == Button1) && (state) && (state == 
screen_info->params->easy_click))
          {

Same for handleKeyPress.
Feel free to comment and criticise!

---
Regards,
Sergey Bolotov