Fixed issue with image buffers not being displayed properly

matron/src/hardware/screen.c

@@ -636,6 +636,9 @@ bool screen_surface_get_extents(screen_surface_t *s, screen_surface_extents_t *e
 
 void screen_surface_display(screen_surface_t *s, double x, double y) {
     cairo_surface_t *image = (cairo_surface_t *)s;
+
+    surface_may_have_color = true;
+
     int width = cairo_image_surface_get_width(image);
     int height = cairo_image_surface_get_height(image);
 

matron/src/weaver.c

@@ -1028,6 +1028,18 @@ int _screen_clear(lua_State *l) {
     lua_check_num_args(0);
     screen_event_clear();
     lua_settop(l, 0);
+
+    // Since screen_event_clear() only puts item a request into a queue it turns
+    // out that the clearing of the screen can actually not be finished until
+    // after the next screen command has started. This is especially apparent
+    // if the next screen command is screen.display_image() for displaying
+    // a buffer. Frequently the end result is that the image buffer is not
+    // displayed at all or only part of it becomes visible. Therefore need to
+    // execute a command that gets a return value to make sure that the screen
+    // has finished being cleared before this function returns. Using
+    // _screen_current_point() here completely fixes the problem.
+    _screen_current_point(l);
+
     return 0;
 }