Created attachment 128314 [details] A project with linear data Fit line renders as vertical segments STEPS TO REPRODUCE 1. Create a New project with some data 2. Create a new fit. Could be linear or not. 3. In fit properties, make sure that line type is "line", style "solid line", "1pt", opacity "100%", without drop lines (the default configuration). OBSERVED RESULT The fit line is not a continuous one but a dashed line with vertical segments. Exporting the graph into a PDF or PNG file shows the same dashed line. SOFTWARE/OS VERSIONS Linux: Linux 5.5.0-2-amd64 #1 SMP Debian 5.5.17-1 (2020-04-15) x86_64 GNU/Linux GNOME Shell 3.36.2 KDE Plasma Version: -- KDE Frameworks Version: 5.62.0 Qt Version: 5.12.5 (built against 5.12.5) ADDITIONAL INFORMATION I'm using labplot 2.7 under Debian unstable (but I tried the same thing with Debian Testing) in Gnome Shell. When I do a fit (linear or any custom fit) the line is rendered as vertical segments. Exporting the graph shows the same problem in the resulting file. When I set the line type as 3-segments I obtain a better rendering. I repeated the process but with the snap version 2.6. It worked well, but when I open this new project with 2.7 from Debian repositories, again the line renders as vertical segments. It seems to be something with the Debian's package. The problem is not data dependent. I tried various datasets and always have the same problem. Neither is it a colour theme dependent problem. It happens with any colour theme.
Debian uses Wayland as default Display server. This leads to several display problems in LabPlot. This needs to be fixed in Wayland (or Qt support of Wayland). Workaround: switch to Xorg (select "GNOME on Xorg" when login)
(In reply to Stefan Gerlach from comment #1) > Debian uses Wayland as default Display server. This leads to several display > problems in LabPlot. This needs to be fixed in Wayland (or Qt support of > Wayland). > > Workaround: switch to Xorg (select "GNOME on Xorg" when login) I was, indeed, using Xorg as Display server. However, I switched to Openbox as window manager and now I have beautiful fit lines in labplot. Thank you so much. I guess Gnome is the problem after all.