shell: reset rotation for maximized surface

Surface will preserve its rotation transformation when maximizing, which
will cause inconsistencies (eg. no window shadows drawn)

This patch removes rotation from maximized surface and restore it when
unmaximizing (just like in fullscreen mode)

src/shell.c

@@ -1472,6 +1472,27 @@ shell_unset_fullscreen(struct shell_surface *shsurf)
 	wl_list_insert(&ws->layer.surface_list, &shsurf->surface->layer_link);
 }
 
+static void
+shell_unset_maximized(struct shell_surface *shsurf)
+{
+	struct workspace *ws;
+	/* undo all maximized things here */
+	shsurf->output = get_default_output(shsurf->surface->compositor);
+	weston_surface_set_position(shsurf->surface,
+				    shsurf->saved_x,
+				    shsurf->saved_y);
+
+	if (shsurf->saved_rotation_valid) {
+		wl_list_insert(&shsurf->surface->geometry.transformation_list,
+						   &shsurf->rotation.transform.link);
+		shsurf->saved_rotation_valid = false;
+	}
+
+	ws = get_current_workspace(shsurf->shell);
+	wl_list_remove(&shsurf->surface->layer_link);
+	wl_list_insert(&ws->layer.surface_list, &shsurf->surface->layer_link);
+}
+
 static int
 reset_shell_surface_type(struct shell_surface *surface)
 {
@@ -1480,10 +1501,7 @@ reset_shell_surface_type(struct shell_surface *surface)
 		shell_unset_fullscreen(surface);
 		break;
 	case SHELL_SURFACE_MAXIMIZED:
-		surface->output = get_default_output(surface->surface->compositor);
-		weston_surface_set_position(surface->surface,
-					    surface->saved_x,
-					    surface->saved_y);
+		shell_unset_maximized(surface);
 		break;
 	case SHELL_SURFACE_NONE:
 	case SHELL_SURFACE_TOPLEVEL:
@@ -1517,11 +1535,6 @@ set_surface_type(struct shell_surface *shsurf)
 		break;
 
 	case SHELL_SURFACE_MAXIMIZED:
-		shsurf->saved_x = surface->geometry.x;
-		shsurf->saved_y = surface->geometry.y;
-		shsurf->saved_position_valid = true;
-		break;
-
 	case SHELL_SURFACE_FULLSCREEN:
 		shsurf->saved_x = surface->geometry.x;
 		shsurf->saved_y = surface->geometry.y;