Yeah, I should have probably explained most a bit more in detail.
I don't think highlight text when long pressing on UI elements is expected behavior for an app though. It would be for a website but can feel out of place in an installed app.
I think any content the user might care to select should be selectable, even if native apps often neglect this feature.
But I agree that UI elements (eg. buttons) should not be selectable. Even in regular websites, it's best to set the whole gamut of appropriate CSS properties so they behave like native UI widgets. I also make sure to set `cursor: pointer` on anything clickable.
Web apps that just set an onclick handler on a div and call it done are a pet peeve of mine.
I don't think highlight text when long pressing on UI elements is expected behavior for an app though. It would be for a website but can feel out of place in an installed app.