Earlier versions of Lotus Notes have also been criticized for violating an important usability best practice that suggests a consistent UI is often better than custom alternative. Software written for a particular operating system should follow that particular OS's user interface style guide. Not following those style guides can confuse users. A notable example is F5 keyboard shortcut, which is used to refresh window contents in Microsoft Windows. Pressing F5 in Lotus Notes before release 8.0 caused it to lock screen. Since this was a major point of criticism this was changed in release 8.0. Old versions did not support proportional scrollbars (which give the user an idea of how long the document is, relative to the portion being viewed). Proportional scroll bars were only introduced in Notes 8.