--- a/ui/win32/toolkit.h	Sat Dec 27 22:47:56 2025 +0100
+++ b/ui/win32/toolkit.h	Thu Jan 08 18:06:04 2026 +0100
@@ -55,6 +55,12 @@
 
 LRESULT CALLBACK ui_default_eventproc(HWND hwnd, UINT uMsg, WPARAM wParam, LPARAM lParam);
 
+typedef void(*ui_command_func)(UiObject *, uint64_t id, void *userdata);
+typedef struct UiCommand {
+    ui_command_func callback;
+    void *userdata;
+} UiCommand;
+
 HFONT ui_win32_get_font(void);
 void ui_win32_set_ui_font(HWND control);