render: search: mark visible portion of sub-surface opaque

quirks.c

@@ -0,0 +1,35 @@
+#include "quirks.h"
+
+#include <stdlib.h>
+#include <stdbool.h>
+
+void
+quirk_weston_subsurface_desync(struct wl_subsurface *sub)
+{
+    /*
+     * On weston (8.0), synchronized subsurfaces aren't updated
+     * correctly.
+
+     * They appear to render once, but after that, updates are
+     * sporadic. Sometimes they update, most of the time they
+     * don't.
+     *
+     * Adding explicit parent surface commits right after the
+     * subsurface commit doesn't help (and would be useless anyway,
+     * since it would defeat the purpose of having the subsurface
+     * synchronized in the first place).
+     */
+
+    static bool is_weston = false;
+    static bool initialized = false;
+
+    if (!initialized) {
+        initialized = true;
+        is_weston = getenv("WESTON_CONFIG_FILE") != NULL;
+    }
+
+    if (!is_weston)
+        return;
+
+    wl_subsurface_set_desync(sub);
+}