Maximum Width For Resizing Locked Column
I think the Grid locked column(s) must be have a maximum width for resizing (Grid.width - VerticalScrollBar.width).
Because when you want to resize locked column more than grid width then you cant see other columns after resizing. Now, if you click on resized column then grid auto scroll to resized width and cannot comeback.
And now, if you double click in resizable vertical column line then this column auto resized and all column disappear from grid.
I test this sample on: Locking Grid Column Example (RTL and LTR mode)