Change in borderstyle property in win 8.1?

When I create a form with borderstyle of dialog it cannot be moved by it's title bar like other windows. This only happens in Win 8.1 not xp, vista, or 7. If I set the property to toolwindow it can be moved. Has there been a change in the function of this property in windows 8.1?

Note: when I first installed windows 8.1 upgrade, icons were stuck wherever they were created. It turns out this was caused by the free fences program. I bought the paid version and it solved the problem. Could this be another problem with fences or has windows changed the backend of how it works on this?

I uninstalled fences 2.12 and the problem persists so it is definitely something that's been done by Windows 8.1.