It looks like you either enabled the hidden HighResUI setting or somehow overrode OpenMPT's DPI scaling from within Windows to allow for that (not sure if that was already an option in Windows 7). You are probably using a scaling factor that doesn't play nicely with OpenMPT's own UI scaling, so it might result in icons becoming a little bit bigger than they should be, so they don't fit anymore on the screen. Also the dropdown buttons on the sample and instrument editor seem to be very wide, which I have only seen once so far on a convertible laptop by another OpenMPT user, apparently this might happen when Windows thinks that you might want to use touch input, and there doesn't seem to be any way for OpenMPT to opt out of that, the buttons will always be larger than intended in that case.
Disabling the HighResUI setting should hopefully fix most of those issues.