Bug 30727 exclusion filters: cannot remove [build path]
20030129 create a jproject and a src folder in it add 2 packages to it a.b and c.d exclude c/d/ from the classpath open the java build path dialog, select the source folders expand the tree node select 'Exclusion filter: /c/d/' press 'Remove' seems to be removed, right? wrong. open the dialog again - the filter for /c/d is still there
org.eclipse.jdt.ui/ui/org/eclipse/jdt/internal/ui/wizards/buildpaths/LibrariesWorkbookPage.java
IProject currProject= fCurrJProject.getProject();
		
		NewContainerDialog dialog= new NewContainerDialog(getShell(), title, currProject, getUsedContainers(existing), existing);
		IPath projpath= currProject.getFullPath();
		dialog.setMessage(NewWizardMessages.getFormattedString("LibrariesWorkbookPage.NewClassFolderDialog.description", projpath.toString())); 
		if (dialog.open() == NewContainerDialog.OK) {
			IFolder folder= dialog.getFolder();
			return new CPListElement[] { newCPLibraryElement(folder) };
		}
		return null;
	}
			
			
	private CPListElement[] openClassFolderDialog(CPListElement existing) {	
		Class[] acceptedClasses= new Class[] { IFolder.class };
		TypedElementSelectionValidator validator= new TypedElementSelectionValidator(acceptedClasses, existing == null);
			
		acceptedClasses= new Class[] { IProject.class, IFolder.class };
		ViewerFilter filter= new TypedViewerFilter(acceptedClasses, getUsedContainers(existing));	
			
		ILabelProvider lp= new WorkbenchLabelProvider();
		ITreeContentProvider cp= new WorkbenchContentProvider();
		String title= (existing == null) ? NewWizardMessages.getString("LibrariesWorkbookPage.ExistingClassFolderDialog.new.title") : NewWizardMessages.getString("LibrariesWorkbookPage.ExistingClassFolderDialog.edit.title"); 
		String message= (existing == null) ? NewWizardMessages.getString("LibrariesWorkbookPage.ExistingClassFolderDialog.new.description") : NewWizardMessages.getString("LibrariesWorkbookPage.ExistingClassFolderDialog.edit.description"); 
		FolderSelectionDialog dialog= new FolderSelectionDialog(getShell(), lp, cp);
		dialog.setValidator(validator);
		dialog.setTitle(title);
		dialog.setMessage(message);
		dialog.addFilter(filter);
		dialog.setInput(fWorkspaceRoot);