Bug 305036 [Path Variables] Minor API changes in Dynamic Path Variables area
I'm attaching a patch illustrating what should be done in this area.
bundles/org.eclipse.ui.ide/src/org/eclipse/ui/ide/dialogs/PathVariableSelectionDialog.java
if (buttonId == EXTEND_ID) {
            PathVariablesGroup.PathVariableElement selection = pathVariablesGroup
                    .getSelection()[0];
			if (currentResource != null) {
				FileFolderSelectionDialog dialog = new FileFolderSelectionDialog(
						getShell(), false, variableType);
				dialog
						.setTitle(IDEWorkbenchMessages.PathVariableSelectionDialog_ExtensionDialog_title);
				dialog
						.setMessage(NLS
								.bind(
										IDEWorkbenchMessages.PathVariableSelectionDialog_ExtensionDialog_description,
										selection.name));
				
				
				IPath selectionPath = selection.path;
				if (currentResource != null)
					selectionPath = URIUtil.toPath(currentResource.getPathVariableManager()
							.resolveURI(URIUtil.toURI(selectionPath)));
	            try {
						dialog.setInput(EFS.getStore(URIUtil.toURI(selectionPath)));
				} catch (CoreException e) {
					ErrorDialog.openError(getShell(), null, null, e.getStatus());
				}
	            if (dialog.open() == Window.OK
	                    && pathVariablesGroup.performOk()) {
	                setExtensionResult(selection, (IFileStore) dialog.getResult()[0]);
	                super.okPressed();
	            }
			}