Wt

When using a WLoadingIndicator implementation that does NOT inherit from WWidget, the member WApplication::loadingIndicator_ is leaked.

class MyLoadingIndicator : public Wt::WLoadingIndicator {
  ...
  ...
  virtual Wt::WWidget* widget() { return whatever_but_not(this); }
  ...
}

setLoadingIndicator(new MyLoadingIndicator(...));

In this case, WApplication takes ownership of whatever widget() returns, instead of taking ownership of the MyLoadingIndicator* itself.

This leads not only to a memory leak, but also leads to trouble if widget() returns the address of a stack object (e.g. member variable of MyLoadingIndicator)

Suggestion: Take ownership of the LoadingIndicator and make the indicator implementation responsible for memory management.