Turning off the App Store gesture? I'm sick and tired of having the App Store launched every other time I try to turn a page in iBook.  Is there a way to turn the stupid "feature" off?  Don't see a setting in the App Store panel, nor in iBooks.

This is a recently added feature.  In any app, a tap or swipe left near the right edge (in other words, the same motion as turning a page) brings in an abbreviated app store panel.  Can dismiss the panel by tapping somewhere else, but my reading is still interrupted, and the full app is still in the background.
I think you're opening Slide Over multitasking on an iPad and App Store happens to be the last app you used with Slide Over.

Instead of sliding from the very edge of the screen, just slide anywhere else on the screen. Start your finger somewhere on the display and Slide Over won't be opened.

You can disable Slide Over completely: Settings → General → Multitasking and turn off Allow Multiple Apps.