Applying C1Theme to form with abstract base class does not work

Applying C1Theme to form with abstract base class does not work

Posted by: wknauf on 17 June 2025, 3:35 am EST

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  wknauf

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  Posted 17 June 2025, 3:35 am EST - Updated 17 June 2025, 3:41 am EST

  We have a form that has an abstract base class in its parent hierarchy.
  
  The theme is not applied to this form.

  See attached sample ThemeControllerAbstract.zip: the class “FormChildSub” has a abstract base class “FormChildAbstract”, which has a base class “FormBase”.
  
  When applying a theme to an instance of “FormChildSub”, the form itself is not themed:
  
  

  

  1242×742 96.5 KB

  It works if the base class is not abstract:
  
  

  

  1189×739 89.1 KB

  I know that it is a bad idea to use abstract forms, because winforms designer cannot handle it. But we have done this years ago, and if we want to edit the child form in designer, we have to remove the “abstract” declaration of the base class and add it again afterwards.

  ILSpy pointed me to this piece of code where a “IsAbstract” check is done:
  
  

  

  733×402 14.1 KB

  Is there any chance to fix theming of forms with abstract base classes? Or is there a reason that makes it impossible for you to support this?

  Best regards

  Wolfgang

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  kartik.dua

  

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  Posted 18 June 2025, 1:59 am EST

  Hi Wolfgang,

  Thank you for sharing all the details. We could see the behavior of C1Themes with the forms having an abstract parent. We have shared all the details with the development team to get their insights on it and will let you know the updates as soon as possible.

  [Internal Tracking ID: C1WIN-34159]

  Best Regards,
  
  Kartik