Counting frames between keyframes

If the second keyframe you click on is to the left then the value is negative and you get the minus sigh. If the second keyframe you click on is to the right you get a positive number. It makes perfect sense to me.

Results are predictable and repeatable if you hold down the Alt/Option key and click on the first one then click on the second keyframe. Sometimes if you highlight a keyframe first and then Alt/Option click on the second one you get the time value for the second keyframe instead of the difference between them.

Also, if the time indicator is set to frames you get frames. If it is set to timecode you get time and some times it's hard to read time and subtract it in your head especially if you are using drop-frame timecode. 99% of my projects are in frames because 99% of my AE work is on a shot and not on something I'm editing because AE is a lousy editor. I'll cut to time in PPro.

A fairly simple expression could be written and applied to the Source Text of a text layer but you would have to declare the layer and the property you wanted to look at every time. If you wanted to check just the time between something like position property on a layer you could use index + 1 to define the layer and then just drag the text layer above the layer you wanted to check. This would save you entering the layer name every time you wanted to check the time between keyframes. It's been a long day so I won't try and write the expression but the logic is this:

p = thisComp.layer( index + 1).transform.position; // looks at the position property of the layer below

Now you would just call out the time value of the previous and next keyframe and then subtract the previous one from the next one. That call would be based on the position of the CTI so you would get a number when th eCTI was between two position keyframes.