I've made the change to the .cpp file but this seems to have had no affect on the window what else do I need to do?
Have you rebuilt the modules after you saved changes. (In MaxIDE, Program ==> Build Modules). You will need to have MinGW installed and set-up properly, otherwise it will not work. See Mark's Post here for more information.
I was looking at this the other day while messing about with a windows properties. This looks like a bug in the gui module which can be fixed by doing the modification in the other thread but surely when the mod gets updated by BRL then it'll need to be edited again as soon as you synchmods and build again?
Just like every time a blitzMax update comes out I have to put the community IDE back in again.
Press Ctrl and D and it will rebuild all your modules. It's always greyed out in the menu as far as I can see but, if you've set up minGW correctly, then it'll do the job.