+// left key update
+void ui_leftkeyupdate(int pressed);
+// right key update
+void ui_rightkeyupdate(int pressed);
+// up key update
+void ui_upkeyupdate(int pressed);
+// down key update
+void ui_downkeyupdate(int pressed);
+// mouse button update (note: 0 = left, 1 = right, 2 = middle, 3+ not supported yet)
+void ui_mousebuttonupdate(int button, int pressed);
+// perform input updates and check for clicks on items (note: calls callbacks)
+void ui_update(void);
+// draw all items of all panels
+void ui_draw(void);
+
+// intentionally public functions:
+// creates a panel