Bug 298835 Merge e4 Project Path Variable back into the 3.6 stream
The virtual folder and filters changes are already in 3.6, the project path variable changes in e4 still remains to be merged.
bundles/org.eclipse.ui.ide/src/org/eclipse/ui/internal/ide/dialogs/PathVariablesGroup.java
private String removeParentVariable(String value) {
    	return ProjectPathVariableManager.convertToUserEditableFormat(value);
    }
    
    /**
     * Commits the temporary state to the path variable manager in response to user
     * confirmation.
     * @return boolean <code>true</code> if there were no problems.
     * @see IPathVariableManager#setValue(String, IResource, URI)
     */
    public boolean performOk() {
        try {
              
            for (Iterator removed = removedVariableNames.iterator(); removed
                    .hasNext();) {
                String removedVariableName = (String) removed.next();
                
                if (!tempPathVariables.containsKey(removedVariableName)) {
					pathVariableManager.setValue(removedVariableName, currentResource, null);
				}
            }
            
            for (Iterator current = tempPathVariables.entrySet().iterator(); current
                    .hasNext();) {
                Map.Entry entry = (Map.Entry) current.next();
                String variableName = (String) entry.getKey();
                IPath variableValue = (IPath) entry.getValue();
                if (!isBuiltInVariable(variableName))
                    pathVariableManager.setValue(variableName, currentResource, URIUtil.toURI(variableValue));
            }