This is actually an issue with Linux. I often have dialog boxes off the screen from all kinds of programs. You can try alt+F7 to see if you can move it otherwise you can just press enter to continue.
Although it won’t help with this issue, there is a later version of Fritzing (0.9.3b) available although possibly not as a package for your os. Upgrading is as easy as downloading the install file from fritzing.org and uncompressing it in to a directory. Works fine on both Ubuntu 16.04 and 18.04 for me.
I have fritzing installed on Ubuntu 18.04.01. It is version 0.9.3(b04.19). When it comes up it is way to big for my 32 inch monitor and it cannot be resized to reduce it’s size to a useable format.
This problem seems to have been around for a while.
Any suggestions?
Some of the things people have tried over the years in the issues on github referred to here may (or may not) help. Otherwise you would have to see if it gets fixed in 9.5 (don’t know of a release date for 9.5.)