There isn't a windows-like tooltip object, but with a little creativity you can make something like it.
What I did was to use a mouse object to determine where the cursor is at a given time. Since I had a bunch of buttons I wanted to tooltip, I used a delayon timer to determine if the mouse was over the button for 3 seconds.
If the timer turned on, then I activated a small panel, which was set up to follow the mouse. ( Panel1.X = Mouse1.X, etc). In the panel was an expression that was the actual text. It was a logical expression, with the "On" being the tooltip text, and "Off" being blank. This way, I could "stack" expressions in the panel, and only have 1 display at a time, based on the mouse's current coordinates.
Hope this helps!