Gesture availability in the app’s bottom region is limited
Aliases: bottom exclusion · tab bar versus home · bottom-sheet start
What it is
Once the system eats bottom-edge swipe-up, everything the app still wants to do at the bottom—switching tabs, opening a drawer, stretching a player to fullscreen—lives in a crack. What remains usable is not “the bottom,” but the strip above the capture band. Start an app gesture inside that band and failure looks like “I swiped and went to the desktop.”
Why it happens
The capture band has height, the tab bar has height, and they often overlap. A tab wants a short tap; swipe-up wants displacement. The system splits on a displacement threshold: too small and the tap goes to the app, too large and it is Home. Tab switches that “slide a little” are then stolen. A drawer designed to pull up from the bottom edge shares a shape with Home and can escape only via speed, a pause, or a second stage (tap then drag). The home-indicator inset is layout yielding to content, not gestures yielding—padding a button higher still lets a further upward swipe from that button enter the system. What the app can do is lift swipe-up starts above the inset and accept that the very edge may always be cut away.
Studying it
In combinations of gesture-nav on/off and tab bar on/off, run “tap the right tab,” “pull the player up from the bottom,” “swipe up to Home.” Log cross-talk. Walk the app gesture’s start upward until it clears the system band, and find the minimum gap. Test the one-thumb bottom reach separately: the reach zone and the capture band are highly coincident.
Where it stops holding
Three-button nav returns the bottom to the app and the limit lifts, but testing only on gesture-nav phones misses a different bottom clash for three-button users (virtual-key misfires). iPad’s bottom gesture strip is thicker; a gap that just clears on a phone is not enough on a tablet. An external keyboard changes the inset, and the capture geometry follows.
Applying it
- For panels that must swipe up, put the handle above the system indicator with a clear gap. Keep tabs as taps; do not make “swipe up to change tab.”
- Honor safe-area layout, then on a real gesture-nav device test where a further swipe up from the button goes.
- Have someone thumb-switch to the rightmost tab, then swipe up from the same place. Switching tabs should not enter multitasking; swiping up from the indicator should not switch tabs. Cross-talk either way means the bottom gestures were not split.