Checks if left button is operated,

sleep @brief: Suspend current thread for a specified milliseconds. its precision is depended on hardware.

modifiers

0:Enable delay, 1:Cancel, 2:Restores, 3: Restores when menu is destroying

change to index arg

set_focus @brief: set a keyboard focus to a window. this may fire a focus event.

will use the key to insert new cat before the first cat with compare less than the key, or at the end of the list of cat and return a ref to that new

le_or_be, true = le, false = be