Wt

Hello Christian,

this is a VERY good catch. No theming is ever applied to the WPanel.

This could be the case for any widget that is set as the WCompositeWidget's implementation. I am however sure I have seen this work for certain other widgets, and am curious as to what the discrepancy is.

Hi Matthias

The Wt- Internal Composite Widgets (like WPanel) work as expected. Because they are a Special Type that is handled in the Theme.

It is different for User Generated Composites.

From what I could figure out, I wrote a Patch, but it really is not a longterm, global solution.

It just targets WBootstrap5Theme, making its apply() function a friend of WCompositeWidget, and in the apply() function, change the widget to the implementation() of the composite Widget.

Breaking SolutionBreaking Solution

class WTheme
{
public:
  class Bootstrap2;
  class Bootstrap3;
  class Bootstrap5;
  ... // rest of class
};

class WTheme::Bootstrap2 : public WTheme
{
  // Bootstrap2 Definition
};
//... others

I made a way better patch...

I added a function to WCompositeWidget to check if the impl_ widget can be cast to a Type:

template <typename T>
bool canCastTo() const {

  if (!impl_) {
    return false; // Cannot cast if no implementation widget exists
  }

  // Perform the dynamic_cast and check if it succeeds
  return dynamic_cast<T>(impl_.get()) != nullptr; 
}

There are concepts for the future, and also static_asserts to make sure the type fits. (left out here)

Within the ::apply() functions of the Bootstrap and Css Theme Classes, I added a check to see if it is a composite:

WCompositeWidget *composite = dynamic_cast<WCompositeWidget*>(widget);

auto panel = dynami_cast<WPanel*>(widget);

if(panel || (composite && composite->canCastTo<WPanel*>()))
{
... // Apply Style
}

Updated the ::apply() Function for WCSSTheme as well as Bootstrap 2, 3 & 5