Windows 7: Text in some apps becomes oversized when using Aero themes

Opting Out of DPI Virtualization

Once you have decided to enable DPI virtualization, you must now scour your system for any DPI-aware applications that lack the corresponding flag, and opt them out of fuzzy bitmap scaling. This reverts them to the XP style scaling they were designed for. There are two ways to do this, one that works only for 32-bit applications and one that also works for 64-bit applications.

32-bit Applications. — This is simple: right-click on the executable in Windows Explorer, select the “Properties” dialog, switch to the “Compatibility” tab, and check the option “Disable display scaling on high DPI settings”. That’s all!
64-bit Applications. — For no apparent reason other than to annoy their 64-bit users, Microsoft disabled the above check box for 64-bit applications, even though the option itself is perfectly functional when set directly in the registry! So you must do the following: start up Registry Editor, navigate to the key HKEY_CURRENT_USER\Software\Microsoft\Windows NT\CurrentVersion\AppCompatFlags\Layers, and add a string value (REG_SZ) whose name is the full path to the application executable and whose value is HIGHDPIAWARE. I recommend that you first modify a few 32-bit applications as described above, so you can see some example values in this registry key.

So that’s how to use high DPI settings on Windows Vista and later. And if you have ever wondered what the option “Disable display scaling on high DPI settings” is for, and why it didn’t do anything on your system, now you know: it’s only effective if you have enabled system-wide DPI virtualization, and then only for applications that are bitmap-scaled because they don’t set the DPI-aware flag.