"As I seem to have misplaced my earlier comment: did you actually verify the various builds on the same machine (excluding the chance that per machine settings are to blame?)
IIRC older Windows versions default to using the mouse for selection rather…"
"OK. It works fine on Windows 7 ultimate 32b (and on Linux 64b but that's not the question). Unfortunately I've got no 64b version of Windows to test it.
And do other text mode programs (FP...) work ?"
You certainly mean older versions of Windows ?
Does the mouse work with other programs in text mode (the Free Pascal editor, for example) ?
If you cannot fix this, you may use the VPC compiler with other editors, like Geany."