Tab Dialogs are special dialog boxes common in Windows 95and later. These dialog boxes simplify controls by separating information into different "folders" with tabs. You can switch between folders by clicking on the appropriate tab. Examples of tab dialog boxes are the Simulation Control, the Equation Editor, and the Control Panel (shown below):
In this picture, the Datasets tab has been selected showing two loaded simulation runs. The Variable, Time Axis, Scaling, and other controls can be selected by clicking on the tab desired.