Creo Options Modeler > References > Fundamentals > User Interface Basics > Working with Creo Parametric Windows and Dialog Boxes > About Ribbon Resizing
  
About Ribbon Resizing
The ribbon resizes automatically when you reduce the width of the Creo Parametric window. During ribbon resize, tab labels are truncated and button labels are hidden. On reducing the width further the groups are compressed until they collapse completely. Each group displays an icon in the completely collapsed state. If you continue to reduce the width after all the groups are in completely collapsed state, a scroll button appears to the right of the groups. As you scroll the groups to the right a scroll button appears to the left of the groups. Similarly, a scroll button is also available for tabs.
The groups collapse according to a preassigned priority index. In the ribbon customize mode, you can modify the priority index.