devdraw: do not interpret alt-tab as alt for compose

R=rsc
CC=plan9port.codebot
http://codereview.appspot.com/5132050

src/cmd/devdraw/x11-srv.c

@@ -36,7 +36,7 @@
 	Button2MotionMask|\
 	Button3MotionMask)
 
-#define Mask MouseMask|ExposureMask|StructureNotifyMask|KeyPressMask|EnterWindowMask|LeaveWindowMask
+#define Mask MouseMask|ExposureMask|StructureNotifyMask|KeyPressMask|EnterWindowMask|LeaveWindowMask|FocusChangeMask
 
 typedef struct Kbdbuf Kbdbuf;
 typedef struct Mousebuf Mousebuf;
@@ -549,6 +549,10 @@ runxevent(XEvent *xev)
 		matchkbd();
 		break;
 	
+	case FocusOut:
+		abortcompose();
+		break;
+	
 	case SelectionRequest:
 		_xselect(xev);
 		break;