Roll-up Buttons (similar to CorelDraw)
BCGControlBar Pro (MFC)
BCGControlBar for .NET
There is a special type of control bars that have an ability to drop down or pop up when the user holds a "top-level" toolbar button for a while. Drop down toolbar button has a small arrow at the right-bottom corner of the button. Drop down toolbars can't be customized, docked or have the tear-off state.
Highlighted roll-up button:
Pressed roll-up button with drop down toolbar: