shell: Make input capture optional for curtains

desktop-shell's focus surfaces want to reuse this, but they don't want
to capture the input, instead allowing it to fall through.

Signed-off-by: Daniel Stone <daniels@collabora.com>

desktop-shell/shell.c

@@ -2092,6 +2092,7 @@ shell_ensure_fullscreen_black_view(struct shell_surface *shsurf)
 		.surface_committed = black_surface_committed,
 		.get_label = black_surface_get_label,
 		.surface_private = shsurf->view,
+		.capture_input = true,
 	};
 
 	assert(weston_desktop_surface_get_fullscreen(shsurf->desktop_surface));

kiosk-shell/kiosk-shell.c

@@ -508,6 +508,8 @@ kiosk_shell_output_recreate_background(struct kiosk_shell_output *shoutput)
 	curtain_params.width = output->width;
 	curtain_params.height = output->height;
 
+	curtain_params.capture_input = true;
+
 	curtain_params.get_label = kiosk_shell_background_surface_get_label;
 	curtain_params.surface_committed = NULL;
 	curtain_params.surface_private = NULL;

shared/shell-utils.c

@@ -173,8 +173,12 @@ weston_curtain_create(struct weston_compositor *compositor,
 	}
 
 	pixman_region32_fini(&surface->input);
+	if (params->capture_input) {
 		pixman_region32_init_rect(&surface->input, 0, 0,
 					  params->width, params->height);
+	} else {
+		pixman_region32_init(&surface->input);
+	}
 
 	weston_surface_set_size(surface, params->width, params->height);
 	weston_view_set_position(view, params->x, params->y);

shared/shell-utils.h

@@ -33,6 +33,7 @@ struct weston_curtain_params {
 	void *surface_private;
 	float r, g, b, a;
 	int x, y, width, height;
+	bool capture_input;
 };
 
 struct weston_output *