OpenFileDialog.Filter
In order to add multiple filters in the same selection, use the semicolon (;):
openFileDiag1 = "Text Files (*.txt);CSV (*.csv);zip files (*.zip)|*.txt;*.csv;*.zip|All files (*.*)|*.*";
You place the display name to the left of the pipe symbol (|), and to the
right of the pipe symbol is the filter used by the OpenFileDialog Control.
In the example above, 'Text Files (*.txt);CSV (*.csv);zip files (*.zip)' will be the first
entry in the 'Files of Type' Combo Box on the OpenFileDialog Control.
'All files (*.*)' will be the second selection in the Combo Box.
