If you downloaded DisplayFusion 12.0 and are having issues with languages please re-download and re-install. We have repacked the release as 12.0c with the languages fixed.
There actually is an option in the Advanced Settings that should help you out. In the TitleBar Buttons section of the Advanced Settings, you can use the "Minimum Window Width" option to set the minimum size a window (enter the value in pixels) has to be before DisplayFusion will add TitleBar Buttons to it
JezE, thanks for that excellent question, and thanks Keith for the solution!
Further to this post, I found that a pixel width size of about 475 px will work well. This width assumes one has about 7 or 8 title bar buttons displayed, and the small dialog boxes in Excel or Word will show up without the title bar buttons. The Format Cells dialog in Excel will show up just fine with the buttons displayed.
Yes, after Keith's guidance, I too found after a little testing that a width of 500 pixels worked best for me and my screens as I have 7 custom Function buttons.