This allows us to share common codes for dealing with osd items.
For example:
- Get the clicked osd item to focus its associated window
- Scroll the items when their total height is taller than output height
- add LAB_WINDOW_TYPE_INVALID in place of literal -1
- document more clearly that enum lab_view_criteria is a bitset
- other one-off replacements of integer values/types for consistency
Note: variables of type enum lab_view_criteria are already used
extensively throughout the code to contain combinations of the declared
enum values. I am not introducing any new usage here, just changing the
single uint32_t to be consistent with all the other usages.
