Segmentation fault with any applied Qt stylesheet when switch off from Transform Module


On Ubuntu 20.04 if I try to apply Qt stylesheet (for example using SandBox style tester with these two default lines) and switch after that I switch to the Transform module and then switch to any other module I get segmentation fault. This makes Qt stylesheets unusable.

Does this happen only on Ubuntu?

I haven’t figured out why this happens only with Transform module but it seems that something related to applying style during qSlicerModulePanel::removeModule:

Thanks for the report :pray:

We should definitely understand the issue and address the problem.

To help move forward with this, could you:

  • share a small standalone example allowing to reproduce the problem. It could be as simple as a list of steps to follow, and few lines that need to be copied into the python interactor
  • provide some context for reproducing:
    • can it be reproduced using the preview package available from
    • is the issue specific to a build of Slicer (if yes, which version of Qt)
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Thank you for reply,

Steps to reproduce:

  1. from extension manager install Sandbox extension;
  2. restart Slicer;
  3. after the restart go to the Modules->Developer Tools->StyleTester and click on Apply to Slicer radiobutton and then click Apply Style pushbutton;
  4. go to the Modules->Transforms (should be fine);
  5. go to any other module (for example Modules->Data) or click Previous modules tool button (here I get segfault)

This can be reproduced on Ubuntu 20.04 with Slicer downloaded from official web-site v4.13.0 built 2022-02-03 or with Slicer manually built with Qt 5.15.2 with GCC 9.3

I just tested that on Windows and it seems that there is no such problem.
But on Ubuntu I get segfault even with the newest Slicer version 2022-03-26

This might be the same thing I ran into with my slicer custom app here: crash when switching out of transforms module · Issue #15 · KitwareMedical/lungair-desktop-application · GitHub

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Yes I think we encountered the same crash.
But it is not only about SlicerCAT but I can see this crash in Slicer app.
Did you ran into this on Linux?

Yes, this was also on Ubuntu 20.04

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