C datagridview cellvalidating example
Column fill mode causes the visible columns in the control to fill the width of the control's display area. There are two kinds of automatic sizing in the Data Grid View control: column fill mode and content-based automatic sizing. The sizing mode for a column is actually determined by its Inherited Auto Size Mode property. To configure the sizing mode for headers and rows and for columns that do not override the control value, set one or more of the following Data Grid View properties: To override the control's column sizing mode for an individual column, set its Auto Size Mode property to a value other than Not Set.
Automatic sizing does not occur when visibility changes, so changing the column Visible property back to true will not force it to recalculate its size based on its current contents.
The new sizes are automatically calculated to display all cell contents without clipping.