There's a memory leak in /drawpic.
It only happens when drawing an .ico file, the problem doesn't appear with .bmps at all.
To reproduce it, use this alias (be warned; you will have to restart mIRC after running /leaktest as it will be completely messed up

):
alias leaktest {
var %x = $+(",$$sfile(c:\*.ico,Choose an icon file),"),%i = 5000
window -pf @leaktest -1 -1 16 16
while (%i) {
drawpic @leaktest 0 0 %x
dec %i
}
close -@ @leaktest
}
Then, try to enter the mIRC setup or open some other dialogs...
Thanks for your attention