I’ll add a preference for that welcome text… but the behavior to open last document has changed.
TaskPaper 2 implemented this manually because OS X had no support for remembering last documents when I built TaskPaper 2. And TaskPaper 2’s behavior was to reopen the last saved document.
TaskPaper 3 uses the OS X default behavior now. Which is that any documents that were open when you last quit TaskPaper will be reopened… so now you just need to quit TaskPaper when you are done, don’t close it’s windows first. Then the documents should be restored. Also if you leave documents open this way folds and selected project will also be restored.
Note that the System General Preference “Close windows when quitting app” can disable this feature.