This function is used to get a mouse message and return immediately.
bool PeekMouseMsg(MOUSEMSG *pMsg, bool bRemoveMsg);
If a mouse message is available, the return value is true.
If no mouse messages are available, the return value is false.
By default, consecutive mouse clicks are recognized as a series of click events. If you want two consecutive mouse clicks to recognize as a double-click event, specify the flag bit EW_DBLCLKS when you create the drawing window.