i'm not entirely sure that i'm following this correctly, but assuming i am: it's the same number of gesture triggers
- old design
- swipe from edge: nav drawer
- swipe from anywhere: switch tabs (or whatever)
- tap back btn: navigate back
- your design
- swipe from edge: navigate back
- swipe from anywhere: nav drawer
- missing input: switch tabs (or whatever)
this i'm also not sure what you're saying? it seems like a good thing to me - it takes up no space, and can be accessed from any height
i wasn't strictly saying that, i was more refuting what i thought your point was: that "it's not a discoverable gesture unless it's tutorialised, because most people won't randomly swipe in from the edge"; which i think in most instances is a very fair point, but in this specific instance i think it is discoverable because the drawer pulls in from the side. (source: i discovered it without a tutorial, or reading the md docs)
I'm not talking about the number of gesture triggers or their discoverability, but rather, their predictability. System Gestures are always on, no matter the screen, the area is defined despite being "invisible". The way it is on top of whatever app is currently on screen makes sense.
A swipe to change tab has the entire content as a "visible trigger", i.e. the gesture will work on any area that is visibly part of the content.
A swipe on cards/list-item (to reply, delete, etc...) has the card/list-item as the trigger area, it is visibly defined.
A swipe from the edge to open a side sheet has a trigger area that extends far beyond the confines of the Hamburger Icon. And if any of the other gestures are present, then the edge gesture conflicts with them. Even worse is, the gesture with no visible area is "on top" of the others that have a predictable area, despite the fact that they exist on the "same plane".
System gestures also don't have a visible area, but again, they work regardless of the current app, and are "on top" of apps. So despite the fact that they also conflict with the other gestures, because they are drawn on top, it doesn't feel as wrong as the side sheet edge gesture.
Like, with the edge gesture to open a drawer, you need to keep the app elements in mind as if there is some physical elevation inside the app. The edge gesture is on top of the tab gesture, and things like that.
With the system gesture, the elevation itself is between the app and the system. Almost like if the system gestures are a glass panel on top of the app. It is a predictable rule.