Why do objects move when editing text?

I have a carefully created Consort diagram for a clinical trial. Boxes with labels joined by arrows.

I have been asked by a journal to add , to it (completely inappropriately but hey).

When I edit it in Omnigraffle, the objects that the labels are attached to KEEP moving despite no reason to. I have to edit and lock the boxes within seconds.

This is intensely frustrating and taking 8x longer than in any other program.

Please help.

It sounds like automatic layout is turned on.

You may have turned it on accidentally, or by choosing a document template that has it on by default. (Templates in the Automatic Layout section of the Resource Browser have automatic layout turned on, the remainder do not.)

To turn off auto-layout, go to the Canvas : Diagram Layout inspector and uncheck the “Automatic layout” checkbox. Does that help?