composite: Automatically enable backing store support on the screen

... unless you explicitly disabled it with -bs on the command line, or
with the corresponding thing in xorg.conf.

v2: Drop a bogus hunk from compChangeWindowAttributes [vsyrjala]
v3: s/TRUE/WhenMapped/ [jcristau]

Reviewed-by: Keith Packard <keithp@keithp.com>
Signed-off-by: Adam Jackson <ajax@redhat.com>

1 files changed, 3 insertions, 0 deletions

diff --git a/composite/compinit.c b/composite/compinit.c
index bc1130e78..64314640f 100644
--- a/composite/compinit.c
+++ b/composite/compinit.c
@@ -355,6 +355,9 @@ compScreenInit(ScreenPtr pScreen)
         return FALSE;
     }
 
+    if (!disableBackingStore)
+        pScreen->backingStoreSupport = WhenMapped;
+
     cs->PositionWindow = pScreen->PositionWindow;
     pScreen->PositionWindow = compPositionWindow;