aI propose an "active layer alpha lock" so that every layer you select during the activation of this mode is alpha locked. Benefits: when jumping from layer to layer you need not worry about acivating or deactivating alpha layers on a case by case basis. In a workflow where you use lock alpha a lot this is much more preferable then doing this tedious activate/deactivate dance. it ensures that you don't add new alpha to any layer for as long as you need that and you don't need to check every time if the lock is active or inactive. Should be a button on toolbar and shortcutable,if possible. a similar implementation to this is in mypaint as a brush mode rather than a layer mode but you cannot use it with other brush modes like multiply or you'd have to build that option in.
I want to make clear I'm not asking for a toggle that remains when I leave the layer. it's a mode that is active on any layer but doesn't mess with or influences the actual alpha lock of that layer. The actual alpha lock should be unchanged.
I'd call it "Preserve layer alpha". It'd be shown as a button right next to the Erase button on the top toolbar, and also have its own shortcut. When it's activated, you can't paint on transparent areas. :) It'd be really handy when you're adjusting colors on existing areas one moment, then have to add a few more opaque areas the next, etc.
yes that is the intended workflow Preserve layer alpha is a decent name
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