I am not sure that I completely understand your requirement. What do you mean by that they are dragging the timebars? Can you tell me what you are describing with "timebars"? Do you mean the thumbs on the selection rectangle that are used for resizing it?
However, display a popup in the application you can use a Popup element and display the selection range inside of it when you drag the desired element. You can take a look at the attached project to see such implementation based on the selection of the timebar. When you drag the selection thumb a Popup element displaying the ActualSelection of the timebar will be opened. Please check this out and let me know if it is what you are looking for.
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