Make the inactive windows less opaque.

This is presently unconditional and is fixed at 2/3 opacity.

This patch depends on xfwm4_prop_deny_wm_opacity_change.patch. Without that
patch, this patch *will* break programs which use things such as Xv
overlays.

Signed-off-by: Darren Salt <linux@youmustbejoking.demon.co.uk>

Index: src/compositor.c
===================================================================
diff -u src/compositor.c src/compositor.c
--- src/compositor.c	(revision 22201)
+++ src/compositor.c	(working copy)
@@ -38,6 +38,7 @@
 #include "screen.h"
 #include "client.h"
 #include "frame.h"
+#include "focus.h"
 #include "hints.h"
 #include "compositor.h"
 
@@ -68,7 +69,7 @@
                                          !FLAG_TEST (cw->c->flags, CLIENT_FLAG_FULLSCREEN))
 #define WIN_IS_OVERRIDE(cw)             (cw->c == NULL)
 #define WIN_IS_ARGB(cw)                 (cw->argb)
-#define WIN_IS_OPAQUE(cw)               (((cw->opacity == NET_WM_OPAQUE) && !WIN_IS_ARGB(cw)) || (cw->screen_info->overlays))
+#define WIN_IS_OPAQUE(cw)               (((calculate_opacity(cw) == NET_WM_OPAQUE) && !WIN_IS_ARGB(cw)) || (cw->screen_info->overlays))
 #define WIN_IS_NATIVE_OPAQUE(cw)        ((cw->native_opacity) && !WIN_IS_ARGB(cw))
 #define WIN_IS_FULLSCREEN(cw)           ((cw->attr.x <= 0) && \
                                          (cw->attr.y <= 0) && \
@@ -166,6 +167,44 @@
     return NULL;
 }
 
+static guint
+calculate_opacity (CWindow *cw)
+{
+    if (!cw->c || cw->c->opacity_locked)
+        return cw->opacity;
+
+    if (FLAG_TEST(cw->c->flags,
+                  CLIENT_FLAG_STATE_MODAL | CLIENT_FLAG_DEMANDS_ATTENTION)
+        ||
+        FLAG_TEST(cw->c->type,
+                  WINDOW_MODAL_DIALOG | WINDOW_TYPE_DONT_PLACE |
+                  WINDOW_TYPE_DONT_FOCUS)
+       )
+        return cw->opacity;
+
+#if 1
+    if (cw->c == clientGetFocus())
+        return cw->opacity;
+#else/* disabled: may cause incomplete redrawing of some windows */
+    {
+        Client *focus = clientGetFocus();
+
+        if (cw->c == focus)
+            return cw->opacity;
+
+        if ( focus && (cw->c->transient_for == focus->window) &&
+             FLAG_TEST(cw->c->type, WINDOW_MENU | WINDOW_TOOLBAR) )
+            return cw->opacity;
+
+        if ( cw->c && focus && cw->c->transient_for && focus->transient_for &&
+             clientGetFromWindow(cw->screen_info, cw->c->transient_for, WINDOW) ==
+             clientGetFromWindow(cw->screen_info, focus->transient_for, WINDOW) )
+            return cw->opacity;
+    }
+#endif
+    return cw->opacity / 3 * 2; /* overflow here is bad :-) */
+}
+
 static gboolean
 is_shaped (DisplayInfo *display_info, Window id)
 {
@@ -1234,10 +1273,12 @@
 
         if (cw->picture)
         {
-            if ((cw->opacity != NET_WM_OPAQUE) && !(cw->alphaPict))
+            guint opacity = calculate_opacity (cw);
+
+            if (opacity < NET_WM_OPAQUE && !(cw->alphaPict))
             {
                 cw->alphaPict = solid_picture (screen_info, FALSE,
-                                               (double) cw->opacity / NET_WM_OPAQUE, 0, 0, 0);
+                                               (double) opacity / NET_WM_OPAQUE, 0, 0, 0);
             }
             XFixesIntersectRegion (dpy, cw->borderClip, cw->borderClip, cw->borderSize);
             XFixesSetPictureClipRegion (dpy, screen_info->rootBuffer, 0, 0, cw->borderClip);
Index: src/events.c
===================================================================
diff -u src/events.c src/events.c
--- src/events.c	(revision 22201)
+++ src/events.c	(working copy)
@@ -1637,6 +1637,7 @@
     {
         TRACE ("focus set to \"%s\" (0x%lx)", c->name, c->window);
         screen_info = c->screen_info;
+        compositorWindowSetOpacity (display_info, c->frame, c->opacity);
         clientUpdateFocus (screen_info, c, FOCUS_SORT);
         last_raised = clientGetLastRaise (screen_info);
         if ((screen_info->params->click_to_focus) && 
@@ -1694,6 +1695,7 @@
         {
             TRACE ("focus lost from \"%s\" (0x%lx)", c->name, c->window);
             clientPassGrabMouseButton (NULL);
+            compositorWindowSetOpacity (display_info, c->frame, c->opacity);
             clientUpdateFocus (c->screen_info, NULL, NO_FOCUS_FLAG);
             /* Clear timeout */
             clear_timeout ();