I'm not sure I can reproduce, could you give the exact steps to reproduce any of the buggy situations on 7.32?

This might be what you are describing, I'm not sure I get it:
A difference between mIRC 6.35 and 7.32 is that using control + a + del to delete the whole content and then using the up arrow key will show that line again with the up arrow on 7.32, while it will show the previous line on 6.35.
I agree that whenever you get the automatic editbox to be a single line, it should allow up/down to work as long as the current line isn't multiline.

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