USB device-mode support (#613)

Modules/lvgl-module/include/lvgl/widgets/toolbar.h

@@ -68,6 +68,16 @@ lv_obj_t* lvgl_toolbar_add_text_button_action(lv_obj_t* obj, const char* text, l
  */
 lv_obj_t* lvgl_toolbar_add_switch_action(lv_obj_t* obj);
 
+/**
+ * Create and add a dropdown to the toolbar actions.
+ * @param[in] obj the toolbar instance
+ * @param[in] options newline-separated dropdown options
+ * @param[in] width the dropdown's width in pixels, or 0 to leave LVGL's default dropdown width
+ * @param[in] text fixed text to show instead of the selected option or NULL to show the selected option as usual
+ * @return an instance created by lv_dropdown_create()
+ */
+lv_obj_t* lvgl_toolbar_add_dropdown_action(lv_obj_t* obj, const char* options, lv_coord_t width, const char* text);
+
 /**
  * Create and add a spinner to the toolbar actions.
  * @param[in] obj the toolbar instance