Defines the file selection mode for the file upload widget.
Possible Values: standard, enhanced, single
Selecting Multiple Files
Certain browsers (such as Firefox and Chrome) support new HTML5 enhancements for file upload controls that make the process of selecting files easier. In these browsers, the user only has to click the Select Files link once. They can then select multiple files from the file browser by holding down the SHIFT or CTRL key while clicking files with the mouse. Also, CTRL+A can be used to select all files in a directory.
In browsers (such as Internet Explorer 8 & 9) that do not support the HTML5 enhancements, the user must select each file individually. To select multiple files, the Select Files link must be clicked again to bring up the file browser when the user wants to select an additional file. This process must be repeated for each file that is added.
Setting this property to 'enhanced' mode attempts to use the HTML5 extensions. If the browser does not support them, the control will behave in 'standard' mode.
Note: the File Upload widget will allow the user to select multiple files even if the "number of files" property is "1". Once they attempt to upload, then the widget will warn them for selecting too many files.
Single Selection Mode
To allow the user to only choose one file at a time, the selection mode, "single" can be used. When using "single" selection mode, choosing another file causes the old choice to be discarded.