I think it has been found useful to be able to identify and list projects which are still designated as 'active' by the user, but don't have any remaining tasks. 'Stalled' is simply the term that has been chosen for this intersection of project conditions. Its definition in OF 1.8 is:

"active but has no remaining actions"

or in Applescript terms:

projects where (number of tasks is number of completed tasks) and (status is active) and ((effectively hidden of its folder is false) or (its folder is missing value)) and (singleton action holder is false)

In earlier builds it was a little more complex - I believe something like:

projects where status is active and ((number of tasks is 0) or ((its number of tasks > its number of completed tasks) and (its number of available tasks is 0))) and singleton action holder is false and ((effectively hidden of its folder is false) or (its folder is missing value))

(Remember that 'active' status is essentially a user choice, rather than a computed condition. Unless, in Preferences, you have checked "When completing the last action - mark the project or group completed", you have to manually change a project's status from Active to On Hold|Completed|Dropped).

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