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
IPathVariable pathVariable = null;
			if (currentResource != null)
				pathVariable = currentResource.getPathVariableManager().getPathVariable(selection[0].name);
			if (info.exists() && info.isDirectory()
					|| (pathVariable != null && pathVariable.getExtensions() != null)) {
				extendButton.setEnabled(true);
			} else {
				extendButton.setEnabled(false);
			}
                
        } else {
			extendButton.setEnabled(false);
		}
    }
	/**
	 * Sets the resource for which the path variable is being edited.
	 * 
	 * @param resource
	 * @since 3.6
	 */
	public void setResource(IResource resource) {
		currentResource = resource;
		pathVariablesGroup.setResource(resource);
	}
	class EnvSelectionDialog extends SelectionDialog {
		ListViewer viewer;
		Object[] extensions;
		protected EnvSelectionDialog(Shell parentShell, Object[] ext) {
			super(parentShell);
			setShellStyle(getShellStyle() | SWT.RESIZE);