There is a feature of Windows 10 that adjusts non-client areas (like title bar) for applications as they are moved between monitors of differing size and DPI.

This feature was supported in Blender in July 2017 but was disabled when we had bug reports. Some Surface Pro computers with Intel graphics cards would incorrectly place their hardware mouse pointer position. The mouse would appear to be at one position but have an effect at a different location, a difference equal to the vertical change in title bar size.

But that was 2 1/2 years ago. It is doubtful that any Windows 10 computer is still using the same bad driver from then. And there is utility in having this feature enabled.

The following illustrates this feature. The top is current behavior, bottom is after this patch is applied.

In each image both Blender and Notepad have been dragged mostly to a monitor with higher scale. Once they make it more than half-way the non-client area (title bar) should change to reflect the DPI of the new monitor. In the top image you see that Notepad does so, while blender stays the same and the titlebar gets disproportionately small. In the bottom image you see that blender behaves as notepad does, adjusting itself to the new monitor. The illustrated change between monitors is only from 100% to 150% scale, but is much more jarring when going to an even higher-dpi monitor.

The plan is that we enable this feature once again and then see if we get any bug reports. If so, we can revert this change again.