Description Page 2020-06-12 13:27:50 EDT

Created attachment 283264 [details]
Sample code to show the issue

Our project has a requirement to use CSS to define colors for Section, including the title foreground color.

Using extension org.eclipse.e4.ui.css.core.propertyHandler, I have provided my own handler and my own element provider through org.eclipse.e4.ui.css.core.elementProvider. However, the handler registered for Section sometimes are ignored.

Further debug shows Eclipse has a SectionElement and handler (org.eclipse.ui.internal.forms.css.properties.css2.CSSPropertyTitleFormsHandler) defined in org.eclipse.ui.forms. Sometimes this handler from Eclipse is found and used instead of my own handler/element.

RegistryCSSElementProvider getElement() should have a better logic to find the needed handler.

I have attached sample program to show the issue.

Note1: I notice the issue is easier to duplicate on Linux than on Win.

Note2: The problem is not consistent. Sometimes my custom handler is invoked; sometimes it is not. I think RegistryCSSElementProvider.getElement() returns the 1st match found; but the order is not always same.