In the VTTES extension, you can choose to have a clear visual display of what layer you're on in one of the corner windows of the map (top left, top right, bottom left, or bottom right). If you're on the Object layer, it says so at a font size you can control, white text on a red background. GM layer is green background. Map layer is yellow background. DL layer is blue. This functionality lets me know at a glance where I am, and needs to be built into Roll20 itself. I don't want to waste time clicking on the toolbar to figure out whether I'm on the Object layer or the Map layer, and I don't want to depend on page opacity to distinguish GM tokens from Object layer tokens. Correspondingly, the VTTES extension lets you choose whether to display a visual, color-coded layer marker on tokens. Same color scheme, and you can decide which layers should have that marker. For example, I have the Object marker off, but the GM marker on, because I want to know at a glance what tokens are hidden from players. Both these pieces of (basic) functionality would make a big quality-of-life difference to Roll20 users, I think.
