Fullscreen & Windowed Issue on Windows 10-- seen here https://i.imgur.com/kT3GPC9.png

Yes, the tool is to be used with the original window size config.

It turns out the issue stems from higher resolutions, like on that of my Microsoft Surface Pro 4. Bumping down the resolution to something like 1920x1080 fixes the issue. 

This was an absolute deal breaker for me. Luckily I have come across a solution in case anyone else (on Windows) wants to fix it on high DPI displays.

This fix is applied on a per-app basis so you won’t have to worry about it affecting apps that don’t suffer from a small GUI.
1. Open the Windows registry editor by typing regedit.exe into Start Menu and navigate to the following location:
Code:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\SideBySide

2. Create a new DWORD value and name it PreferExternalManifest. Double click it and set its value to 1.
3. First, open the application folder for the application you need to fix the GUI for.
4. Copy below codes and paste it in notepad.

Code:

<?xml version="1.0" encoding="UTF-8" standalone="yes"?>  <assembly xmlns="urn:schemas-microsoft-com:asm.v1" manifestVersion="1.0" xmlns:asmv3="urn:schemas-microsoft-com:asm.v3">  <dependency>   <dependentAssembly>     <assemblyIdentity       type="win32"       name="Microsoft.Windows.Common-Controls"       version="6.0.0.0" processorArchitecture="*"       publicKeyToken="6595b64144ccf1df"       language="*">     </assemblyIdentity>   </dependentAssembly> </dependency>  <dependency>   <dependentAssembly>     <assemblyIdentity       type="win32"       name="Microsoft.VC90.CRT"       version="9.0.21022.8"       processorArchitecture="amd64"       publicKeyToken="1fc8b3b9a1e18e3b">     </assemblyIdentity>   </dependentAssembly> </dependency>  <trustInfo xmlns="urn:schemas-microsoft-com:asm.v3">   <security>     <requestedPrivileges>       <requestedExecutionLevel         level="asInvoker"         uiAccess="false"/>     </requestedPrivileges>   </security> </trustInfo>  <asmv3:application>   <asmv3:windowsSettings xmlns="http://schemas.microsoft.com/SMI/2005/WindowsSettings">     <ms_windowsSettings:dpiAware xmlns:ms_windowsSettings="http://schemas.microsoft.com/SMI/2005/WindowsSettings">false</ms_windowsSettings:dpiAware>   </asmv3:windowsSettings> </asmv3:application>  </assembly>

6. Save the manifest file with manifest extension. For example, Photoshop has a small GUI and Photoshop executable file is called Photoshop.exe. Note the name for the executable file. Next, rename the manifest file you just downloaded to Photoshop.exe.manifest. Copy this file to the same location as the Photoshop.exe file.
You will need administrative rights to do this. That’s all you need to do.