Please help: Replace selected file name with string

[Gintaras]

BrowseForFolder usually is used only for folders. For files use OpenSaveDialog. It allows you to specify file types. You probably use BrowseForFolder because need both files and folders. You can download the latest Quick Macros version and use menus. Now menus can be used instead of standard file/folder selection dialogs, and you may find it faster. Usage examples - Run Program dialog (function TO_FileRun), Open Folder dialog, and some other dialogs from the floating toolbar.

I get an error message saying "this destination does not support long file names"

This message is not generated by QM. If long filenames are not supported, format the filename differently.

Is there a way to limit file selection to certain file types/extensions (e.g., MP3, WAV

BrowseForFolder does not allow it. Use OpenSaveDialog, or QM 2.2.0.9 and menu.