I have the problem that the DataGridView has obviously a shortcut key for SHIFT + SPACE which seems to select the row.
What I would like to have is that pressing SHIFT + SPACE simply adds a space character to the current cursor position within the current cell (like for example in notepad)
Just found out a way which works well for me.
According to http://msdn.microsoft.com/en-us/library/tb9t9a2t.aspx this shortcut key is just applied when RowHeaderSelect or ColumnHeaderSelect is used as SelectionMode - so i just changed it to CellSelect