Locking layers

[johnwdubois]

Goal

• A layer may have very high value to the user, so a secure method is needed to prevent accidental deletion.
• Layers should be positively locked by default.
• Locking should be applied from the very first content-oriented action in a new layer.

What to do

1. When a new layer is created, and a user makes a link, chain, etc., set LayerHasContent = TRUE.
2. If a user (or the app) tries to delete a layer, show a scary dialog box with details on how much content there is in the layer.
3. Before setting LayerHasContent = FALSE, test carefully to make sure there is no content at all.
4. Don't delete a layer unless all its content is deleted first, and LayerHasContent = FALSE.
5. When initializing a new layer and/or sorting out the legacy "Default" layer situation...

• cycle through each layer, test for content, and if found, set LayerHasContent = TRUE
• for layers with no content (e.g. newly created layers), set LayerHasContent = FALSE
• make a list of layers with LayerHasContent = TRUE
• make a list of layers with LayerHasContent = FALSE
• if the length of the TRUE list is = 0, delete all but one of the layers in the FALSE list
• if the length of the TRUE list is > 0, delete all of the layers in the FALSE list