Losing projects when dragging between documents

I’ve encountered what appears to be a bug that occurs when dragging projects from one document to another. I am running TaskPaper 3.3.1 from the Mac App Store on OS X 10.11.5.


  • Create 2 documents (A and B) each containing a couple of projects and child items
  • Drag a project from document A to document B, from sidebar to sidebar
  • Drag the project from document B back into document A

Expected result:
The final versions of the documents are unchanged, as the project was moved and then put back into document A. The project was added to document B and then removed from document B.

Real result:
The project and children from document A are moved (not copied) to document B on the first drag and drop. When dragged from B to A, the project simply disappears from both documents and cannot be recovered via undo.

Overall, I have found that dragging objects between documents has very uneven - and untrustworthy results. Variations on this recipe will yield different results, all of which may result in a loss of data during drag and drop operations.

I’m not able to recreate this in the default “Welcome” document. Here’s what I’m doing:

  1. Create two new documents with default “Welcome” text content
  2. Drag the “Welcome” project from sidebar A to sidebar B
  3. Drag that same “Welcome” project back from sidebar B to sidebar A

For me (TaskPaper 3.3.1 macOS 10.11.5) this seems to work fine and undo state and behavior seems correct.

This is odd, I think it’s the first that I’ve heard about drag and drop bugs, I don’t “think” it’s a general problem. Few thoughts:

  1. Can you create a simplest case example document and set of instructions that reproduces the problem and post that to this thread.
  2. Does this problem also happen in your Guest user account?

Hi Jesse. Thanks so much for your speedy reply!

I have duplicated this problem on 2 different Macs, each running 10.11.5. One is my 2014 MBP retina, and the other is my old, heavy low-res 2012 MBP.

I have tried this while logged into a Guest account as well - same results.

I observe that if I drag all the projects out of a file, the file becomes empty. When this file is opened in some neutral text reader (e.g., TextWranger) it displays only the text “undefined”.

I am attaching 2 very small files, A.taskpaper and B.taskpaper. These have worked reliably to reproduce this issue.

I made a short movie that illustrates this issue “in action” as well:

I see that this Dropbox link doesn’t play nice with video controls. I hope you can simply download it - about 5.3MB.

B.taskpaper (75 Bytes)
A.taskpaper (75 Bytes)

The movie plays if you get to the context menu and choose “open in new window”. Ah, Dropbox.

Thanks for the video, I am able to reproduce the problem. The difference between what I was doing and what you are doing is that you were selecting the project B2 before moving it. Of course it should work, but that’s the part that I wasn’t doing originally. I’ll see if I can get a quick fix in for this.

I’m glad the video helped. I know that very small bits of interaction changes can make all the difference, and it wouldn’t have occurred to me to say “select the project” as a separate action - I’m blind to all the little things I do so often!

I love the way TaskPaper works, and thanks for what you do.

I’ve just posted a new preview version that I think will fix these issues:

Can you give it a try and let me know if it does?

Just tried preview version 218, and it appears to work just fine. I can drag and drop projects between docs all day long. Thanks for such quick work!

I use this as a way to “carry over” projects from one 2-week period to another. Whatever projects still have undone items get dragged to my next 2-week TaskPaper planner. There’s probably a way to script that, but this method forces me to review what the hell it is I’m doing.

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