vertical cursor glitch - vulnerability or benign?

I had a cursor glitch, where the cursor appears like a vertical dotted stripe. Is this necessarily a vulnerability, or could it just be a benign problem from graphics toolkits? It's less likely to be solely xorg, or video drivers.

In the past, this glitch never seemed happen on FreeBSD, but later it only happened when Flash Player was installed. Then earlier this year, it happened after installing a game games/0ad, which I haven't used any more.

Most recently, which is concerning, this happened with common desktop office applications, perhaps narrowed down after switching to graphics/qiviewer after trying to avoid using gtk3. It seems a few programs are buggy. Is it likely that a horizontal cursor is a benign issue, where the toolkit lapses to draw it properly, or is it likely it is hinting at a vulnerability problem?

I'm wondering if this is caused when two toolkits or different versions of toolkits are used, and they possibly conflict with each other. Even though I only have gtk2, maybe this could be because I set options for gtk3, before deciding not to install it.