I run gVim from the command line and have for many, many years. But ever since upgrading to Ubuntu 18.04, I keep getting a long string of this warning a while after starting gVim:
** (gvim:5924): WARNING **: 15:10:26.274: invalid source position for vertical gradient
It's rather annoying because I keep using the terminal afterward and would like the content that was there before to stay there.
I haven't found anything useful searching for this warning online. I have no idea where it comes from or what it means.
Any help really appreciated.
This can be caused by an incompatibility or bug of the selected gtk theme and/or the version of the gtk theme engine. You should be able to get rid of the error by switching to another theme, preferably the default theme that comes with your distribution.
Although not directly related, this bug report may be able to help understanding the underlying problem: https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=751735