xwindow: introduce vwm_xwin_should_manage()

Preparatory commit for applying a heuristic to honoring
override_redirect.

The X11 specification more or less requires honoring this window
flag, but it's really a disaster to blindly do so.

This function will be used to evaluate override_redirect wherever
it's currently being directly used to determine wether a window
should be managed or not.

As-implemented it only ignores override_redirect when the window
dimensions match its screen dimensions (fullscreen windows).  In
the future this might get loosened up a bit to encompass windows
covering more than something unexpectedly large for a
tooltip/popup, like 50% of the screen, since valid
override_redirect uses should arguably be limited to small
windows.

2 files changed, 30 insertions, 0 deletions

diff --git a/src/xwindow.c b/src/xwindow.c
index 18ebf5f..a682e9f 100644
--- a/src/xwindow.c
+++ b/src/xwindow.c
@@ -109,6 +109,35 @@ void vwm_xwin_setup_chart(vwm_t *vwm, vwm_xwindow_t *xwin)
 	}
 }
 
+/* override_redirect windows typically should not be managed, and it'd be nice if we could
+ * just blindly respect that, but X is a dumpster fire and for multiple reasons I'm going
+ * to use some heuristics to only not manage override_redirect windows when they're substantially
+ * smaller than the size of the display (popup/popover type shit).
+ *
+ * When any old X client can create a fullscreen override_redirect window it not only makes
+ * fullscreen games and shit not explicitly focusable/managable from a vwm perspective, it
+ * also creates a real potential security issue.
+ */
+int vwm_xwin_should_manage(vwm_t *vwm, vwm_xwindow_t *xwin)
+{
+	const vwm_screen_t	*scr;
+
+	if (!xwin->attrs.override_redirect)
+		return 1;
+
+	scr = vwm_screen_find(vwm, VWM_SCREEN_REL_XWIN, xwin);
+	if (!scr)
+		return 1;
+
+	/* TODO: for now just using an exact fullscreen heuristic, but should really
+	 * trigger for > XX% coverage.  This suffices for managing annoying
+	 * override_redirect fullscreen windows.
+	 */
+	if (xwin->attrs.width == scr->width && xwin->attrs.height == scr->height)
+		return 1;
+
+	return 0;
+}
 
 /* creates and potentially manages a new window (called in response to CreateNotify events, and during startup for all existing windows) */
 /* if the window is already mapped and not an override_redirect window, it becomes managed here. */
diff --git a/src/xwindow.h b/src/xwindow.h
index 1318421..65d0725 100644
--- a/src/xwindow.h
+++ b/src/xwindow.h
@@ -41,6 +41,7 @@ void vwm_xwin_message(vwm_t *vwm, vwm_xwindow_t *xwin, Atom type, long foo);
 vwm_xwindow_t * vwm_xwin_lookup(vwm_t *vwm, Window win);
 int vwm_xwin_is_mapped(vwm_t *vwm, vwm_xwindow_t *xwin);
 void vwm_xwin_monitor(vwm_t *vwm, vwm_xwindow_t *xwin);
+int vwm_xwin_should_manage(vwm_t *vwm, vwm_xwindow_t *xwin);
 vwm_xwindow_t * vwm_xwin_create(vwm_t *vwm, Window win, vwm_grab_mode_t grabbed);
 void vwm_xwin_destroy(vwm_t *vwm, vwm_xwindow_t *xwin);
 void vwm_xwin_restack(vwm_t *vwm, vwm_xwindow_t *xwin, Window new_above);