If you hold either mouse key (Tested with right and left keys, I don't have a middle one) and then leave a window, mIRC will continuously send leave events until you let go of the key, to reproduce:
alias testing { window -dp @test }
menu @test {
leave:{
echo -s Left $leftwin
}
}Type
/testing, then press and hold either key inside @test, move out of the window whilst still holding the key and then look in the status window, it should of flooded with "Left @test".
