function GetOpenFileName(const Prompt: String; var FileName: String; const InitialDirectory, Filter, DefaultExtension: String): Boolean;
Displays a dialog box that enables the user to select an existing file. Returns True if the user selected a file, False otherwise. The name of the selected file is returned in the FileName string.
An example Filter: 'Text files (*.txt)|*.txt|All files (*.*)|*.*'
var
FileName: String;
begin
// Set the initial filename
FileName := '';
if GetOpenFileName('', FileName, '',
'Text Documents (*.txt)|*.txt|All Files|*.*', 'txt') then
begin
// Successful; user clicked OK
// FileName contains the selected filename
end;
end;