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 void updateWidgetState(String selectedVarName) {
        updateVariableTable(selectedVarName);
        updateEnabledState();
    }
    /**
     * @param resource
     */
    public void setResource(IResource resource) {
    	currentResource = resource;
        if (resource != null)
        	pathVariableManager = resource.getProject().getPathVariableManager();
        else
        	pathVariableManager = ResourcesPlugin.getWorkspace().getPathVariableManager();
        removedVariableNames = new HashSet();
        tempPathVariables = new TreeMap();
        
        initTemporaryState();
    }
	/**
	 * Reloads the path variables from the project description.
	 */
	public void reloadContent() {
        removedVariableNames = new HashSet();
        tempPathVariables = new TreeMap();
		initTemporaryState();
		if (variableTable != null)
	        updateWidgetState(null);
	}
}