#If MouseIsOverTitlebar()
XButton1::
IfWinNotActive, ahk_class mpv
    Send {t}
ControlSend,, {t}, ahk_class mpv
return


MouseIsOverTitlebar() {
    static WM_NCHITTEST := 0x84, HTCAPTION := 2
    CoordMode Mouse, Screen
    MouseGetPos x, y, w
    if WinExist("ahk_class Shell_TrayWnd ahk_id " w)  ; Exclude taskbar.
        return false
    SendMessage WM_NCHITTEST,, x | (y << 16),, ahk_id %w%
    WinExist("ahk_id " w)  ; Set Last Found Window for convenience.
    return ErrorLevel = HTCAPTION
}