Editing Timeline Clips by Entering Precise Duration Numbers?

I'm creating a video from a series of images using Photoshop CC on Windows 7. I'd like to be able to adjust the duration of the clips in the Timeline by entering precise numbers, rather than dragging the clips' handles, but this seems possible only in limited circumstances.

I have a Timeline in Photoshop with several Video Groups, each of which contains a series of clips of images or text. Often, after adding the images/text and inserting transitions, I realize the pacing is off and I need to adjust the duration of many of the clips. I can obviously do this by dragging the handle at the beginning or end of each clip, but this is both cumbersome and difficult to get the exact duration I want.

If I right-click on a Transition, there's a pop-up window that allows me to enter the exact duration I want for the Transition. If I right-click on a clip that has no content, I get a pop-up window that allows me to enter both duration and speed. But if I right-click a clip that includes content (an image or text), I get a pop-up window titled Motion with a drop-down to set pan, zoom, etc., but does not allow me to edit the duration of the clip.

Am I missing something? Is it possible to edit these clips by entering a numerical value for the duration?

Thanks.