Does anyone know if Mathworks allows to get the current ColumnWidth values yet?
An answer is not trivial. Do you mean "The Mathworks" or "Matlab"? While I'm sure that the company will allow this freely, Matlab does not have the power to do this directly. When you cannot use 3rd party code, the only way I see is a screenshot and counting pixels between the bars. This can be done with "native Matlab functions", but I would hesitate to implement it.