When I have a DataGridView on a Windows Form, is there a way to use my mouse to simply drag a column to a proper width, instead of doing it programmatically or by manually typing in the size?
[Edit] This question is referring to design-time editing of a column width.
No, there simply is no support for this.
Most likely because it was considered unnecessary.
Tweaking the numbers (Width and FillWeight) is much more productive.