Created attachment 95628 [details] example 1 Sometimes when Plasma is freshly started I see "strange font effects" on Plasma tooltips, see attachments. I cannot reproduce it. It just happens sometimes. Restarting Plasma fixes the problem.
Created attachment 95629 [details] example 2
Created attachment 95630 [details] example 3
Urgh. Thanks. Can you tell me what graphic card you're using?
Nvidia GeForce GT 330M/PCIe/SSE2
It did not happen again since the last comment, I close the issue for now.