In the current version of the Docking control, the width/height of the Pane cannot be restricted at this stage - setting MaxWidth/MaxHeight does not affect the resizer and the Pane can still be resized.
However, an easier task is to remove the Resizers completely.
Please find attached a sample project illustrating how to remove the Resizers for the LeftAutoHideArea. You could do the same for all others if needed.
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