Per-tab outlines was recently implemented in e705330.

Which means currently we have locked sidebars based on tabpage IDs, through outline.sidebars[id]. The idea of this issue is to let the user choose other options in locking the outline.

After invoking a locking command, outline content will not automatically change.

• buffer: outline auto updates for text changes in current buffer only
• window: outline auto updates for all buffer switches within same window only
• tab: outline auto updates for all buffer switches in current tab only (default)
• ft: only update outline content if the new buffer has the same ft

these can be subcommands to :OutlineLock

with no subcommands it could lock the outline content so it doesn't auto update on text change

:OutlineUnlock restores current behaviour

Running lock after a previous lock command, is equivalent to running first lock, running unlock, then running second lock. (so no accumulation of lock rules)

there will be no cleverness or internal magic that lets :OutlineLock use the previous lock subcommand if second run did not provide subcommand.

config:

• outline_items.lock: nil/false is current behaviour. a string value means a lock rule to be used by default when outline is first set up.