iTools displays "No Valid LangCat"

Problem: 

If you are using iTools to visualize some data (for example using iimage), it is possible for all the menu items to say "No Valid LangCat" instead of what they should say.

Solution:

This usually indicates that IDL is unable to find the catalog files located in the directory shown below:

IDL_DIR/resource/langcat/itools

There are a couple of reasons why IDL might be failing to find these files. The first possible cause of the issue is that the files do not exist. Therefore, the first solution is to confirm that the files exist in this directory. If the files do not exist, you can try re-installing IDL and see if that helps with the problem. 

Another possible cause of the problem is the IDL search path may not include the directory with the language catalogs. The IDL_PATH preference should include an "<IDL_DEFAULT>" tag. This tag adds all the standard paths to the IDL Search Path that are needed to run IDL properly. You can check this using the PREF_GET command as shown below:

IDL> print, pref_get('idl_path')
<IDL_DEFAULT>;C:\Exelis\se51\lib;C:\Users\username\dj_dialog_editor;

If the "<IDL_DEFAULT>" tag is not included int he IDL search path, you can add it to the path using the PREF_GET, PREF_SET, and PATH_CACHE routines. For example:

path = PREF_GET('idl_path')
new_path = '<IDL_PATH>' +  path_sep(/SEARCH_PATH) + path
pref_set, 'idl_path', new_path, /commit
path_cache, /rebuild

Review 12/11/14 by DS and KK