I skipped past somewhere that referred to a counter which recorded this info in one or more variables. Will try my best to find it again but failing that it would be pretty easy to create a Profile/Task in Tasker to record this info for you. There are a few Logcat Entries that change based on the Fold position, for example:
Component = DisplayFoldController
Filter = FoldStateChangedEvent: foldState=x
Where x is,
0 = Closed
2 = Half Way Open
3 = Open
This is from memory but I'm pretty sure it's correct as I use it myself. It was one of the better Logcat Entries I found as it also gives the 'half way open' state.
Using this and setting some variables you can pretty easily clock the amount of time you open it...
Hope this helps a little! ππΌ
