Occasionally, I run into a problem in LibreOffice Writer in which any dialogue box or drop-down menu I open is blank and I cannot select text in the document. For example, if it’s a new document and I try to exit, the dialogue box that pops up asking me if I want to save it has a title bar that says “Save Document?” but is otherwise blank. It also won’t let me quit. If I want to change the font, the dropdown menu is blank. I also can’t select any text within the document with the mouse. I can still type and use the buttons in the toolbar at the top that don’t involve a dropdown menu, and I can even save documents (the “Save As” window works without any problems), but I can’t seem to close windows I don’t want to save without using the System Monitor. I installed Ubuntu 16.04 a couple weeks ago and LibreOffice Writer has been having these problems since I started using it then.
Did you try to disable “OpenGL” and Hardware Accelerator in Tools → Options? It helped me with these problem on Ubuntu. Specially OpenGL… and don’t forget to restart LibreOffice to check if the problem is solved (temporary disable QuickStarter and exit all LibreOffice programs).
OpenGL was disabled by default. Enabling it didn’t help, it just made everything look glitchy.
For the record, this problem was solved for me by upgrading to LibreOffice version 5.4 from the default version 5.1 shipped with Ubuntu 16.04.