Multiple Initial-Files in [tk

The tk_getOpenFile command has a -multiple option, which allows multiple files to be selected in the dialog. It also has an -initialfile argument. However, at the present time, at least on Unix, it is impossible to have multiple files selected initially with -initialfile. This TIP proposes that -initialfile take a list of files if -multiple is also passed as an argument. As it is possible to select multiple files, it should also be possible to have multiple files be selected when the widget is created via the -initialfile switch. If the -initialdir value is not a well-formed path name in its filesystem (for instance, if a component name contains a null byte or a character that is not permissible), the behavior is as if -initialdir was not specified. If the object designated by the -initialdir value does not exist, or if it is not a directory, nor a symbolic link to one, the behavior is as if -initialdir was not specified. If the -initialdir value is the empty string, the behavior is as if -initialdir was not specified. If -multiple 0 is specified, or tk_getSaveFile was called, the -initialfile value is interpreted as a file name. If -multiple 1 is specified to tk_getOpenFile, the -initialfile value is interpreted as a list of file names. A list that is not well formed (for example, one containing unbalanced braces) is not an error, but instead causes the -initialfile option to be ignored. For each file name in the -initialfile value, the system joins the directory provided on the -initialdir option (or the current working directory if no -initialdir is supplied) with the -initialfile. The resulting path name is normalized as with file normalize and then separated into directory and tail components as with file dirname and file tail. Any errors in this process cause the file name to be ignored. Once the file name is separated into its components, the directory part is checked: If the -initialdir option was supplied, and the directory part of the file name differs from the result of normalizing the -initialdir value, the file name is ignored.If the -initialdir option was not supplied, and the directory part of the file name designates a directory in the file system, the -initialdir value is set to that directory. Otherwise, (since the file cannot exist), the file name is ignored.If the given file exists, or if tk_getSaveFile was called, the tail part of the file name is added to a list of files to select within the initial directory. Once -initialdir and -initialfile have both been parsed, the initial directory is known, and the list of initial files is identified; the files are known to be relative to the initial directory, and (for tk_getOpenFile) are known to exist.