In today's nugget, I'm going to talk about .mnu files, which define the hierarchy for the Controls and Functions palettes in LabVIEW. There are three primary locations where you would find .mnu files on your machine:
- [LabVIEW]\menus - This is the main location for almost all .mnu files. This folder contains .mnu files installed with core LabVIEW, modules/toolkits, and some 3rd-party LabVIEW add-ons.
- [LabVIEW]\user.lib - Any .mnu files in this folder will be used to populate the contents of the User Controls subpalette of the Controls palette and the User Libraries subpalette of the Functions palette.
- [My Documents]\LabVIEW Data\{version}(xx-bit)\Palettes\menus - If you ever change the contents of your palettes with the Tools > Advanced > Edit Palette Set utility, any changes you make will be stored in this location, and these changes will override the contents of [LabVIEW]\menus when the palettes are loaded.
In the past we have supported other locations for .mnu files, but support for locations other than the three mentioned above is mostly deprecated at this point.
So how do .mnu files work? The file format is an internal LabVIEW file type that stores all the information LabVIEW needs to construct a palette...the palette icon, the contents of the palette, the type of each palette object, and links to .mnu files that define any subpalettes on that palette. Paths to subpalette .mnu files are stored as relative paths within an owning .mnu file. Paths to VIs and CTLs in vi.lib are stored as relative to vi.lib. The palette API (Read Palette.vi and Write Palette.vi) provide programmatic access to all the information stored in .mnu files.
Finally, let's discuss a curious entity you might find when you start browsing around [LabVIEW]\menus...dozens of empty text files called 'readonly.txt'. The filename is a misnomer...it is a relic of some old palette editing functionality. At this point, these files really only serve one purpose. There are some hard-coded palette items within the core LabVIEW palette set. This is because we want to enforce an intuitive palette layout when you install modules and toolkits. So the positioning of some module and toolkit subpalettes are actually defined within the core LabVIEW .mnu files. So what happens if a particular module/toolkit is not installed? As a general rule, if something in a .mnu file cannot be found when LabVIEW is loading the palettes, a big "?" appears in its position in the palettes. The presence of the 'readonly.txt' file simply prevents these question marks from appearing. This behavior occurs within any palette defined by a .mnu file that has a 'readonly.txt' file sitting next to it on disk. If you delete all the 'readonly.txt' files from your [LabVIEW]\menus folder, a bunch of question marks will appear within your palettes where empty space used to be.
If you're interested in how you might plug in to the LabVIEW palettes for your own add-ons, check out the Creating a LabVIEW Palette article on the NI Community website.
Message Edited by Darren on 06-15-2010 06:50 PM
