Bug 305004 The PathVariableSelectionDialog should not use 'Extend' to build path variable arguments
The PathVariableSelectionDialog should not use 'Extend' to build path variable arguments, since this is used already to build a path, which could be used to build a path starting off an argumented path variable.
bundles/org.eclipse.ui.ide/src/org/eclipse/ui/ide/dialogs/PathVariableSelectionDialog.java
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();
            }
			}
        } else {
			super.buttonPressed(buttonId);
		}
    }