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public virtual int ThumbsHitTestBuffer { get; set; }
The hit test buffer, in annotation coordinates, for the thumbs of this AnnEditDesigner. This must be a value greater than or equal to 0. The default value is 1.
The hit test buffer is used to make the test point "bigger" to compensate for errors and provide smoother hit-testing. For example, if the buffer value is 2, a square with a length of 4 pixels around the test point will be used to perform the hit-testing.