Steps to reproduce:
1. create a New Project with any older version of Unity than 5.4.0f1
2. close the project
3. go to Control Panel > type "make text and other items larger or smaller" into search field > select Make text and other items larger or smaller
4. under "Change only the text size" select "Tile bars" and set the size to 20. Apply settings
5. open Unity 5.4.0f1 or newer
6. Select project that was created before

Result: Continue/Quit buttons are missing in the dialog (see pictures)

Reproduced with: 5.5.0a6, 5.4.0p2, 5.3.6p2, 5.2.5f1

Note:
-bug appears every time when a project (previously saved with different version of Unity) is opened
-also the shape of dialog box are not rectangle (see pictures) when changes for scene were made and trying to close the project