If you are having trouble with files being downloaded in ASCII mode, you can try adding this setting to prefs.js:
user_pref("browser.download_unknown_as_binary", true);

If repeated opening and closing of Netscape 4.61 causes lockups for you, there is a solution that has worked well for some people. Rename the WPS drag & drop module (NS46DRAG.DLL) so that it does not load.

If you are having problems with Netscape using 100% CPU utilization, make sure that your disk cache is not set to zero, even if you are using another form of cache.

Before adding these lines to your prefs.js, BACK IT UP! If you make a mistake, you could lose it.

user_pref("toolbar.logo.frames", 33);  // Number of frames
user_pref("toolbar.logo.win_large_file", "d:\\webexl.bmp"); // Location of large bitmap 
user_pref("toolbar.logo.win_small_file", "d:\\webexs.bmp"); // Location of small bitmap

Pressing Ctrl-Alt-T opens a popup window that displays the status of connections in use by Netscape.

You will find a page with links to most of the plugins that work with Communicator/2 here. Note that it hasn't been updated in a long time.

Duane has cleaned up the Netscape icons, so that they display better at all resolutions. This will likely be included in some future version of the IBM distribution, but until then, you can apply them with Duane's package. The APPLYICO.CMD file also changes the Communicator icons titles (removes the word "Netscape").

pref("SpellChecker.DefaultLanguage...blah blah
pref("SpellChecker.DefaultDialect...blah blah

Note these lines get added back sometimes when you use the spellchecker on 4.04.

If you insert in prefs.js the line:

user_pref("mailnews.start_page.enabled", false);

then Netscape NetCenter will not display every time you start Messenger.

"Kiosk mode" provides a way to lock down Netscape and remove many user control elements. The normal kiosk mode is invoked using the -k option. For example:
NETSCAPE -k http://cnn.com/

It's also possible to remove the title bar from the browser window by using this undocumented (or at least poorly documented) option:
NETSCAPE -k1 http://cnn.com/

To get a stock quote, just type "quote stock_name" in the location bar. Other location bar features, like "smart browsing," also work

user_pref("os2.drag_menu", true);

Typing "about:config" (no quotes) in the URL bar shows a list of several Communicator preferences and their current values. You can look through these and add what you want to your prefs.js file. This is color coded; it appears that black items are hard-coded, blue items are changed from default value, and green items are at default value.

OK, the following CMD file is a catch all for all of the above. First the CMD file:

/* IniName points to the location of your NSCP.INI */
/* Change NSDir to the directory where NS40 is installed */
/* Change InstallDrive to the drive where NS40 is installed */
/* Change en to be the two character identifier for your browser */
IniName = 'C:\OS2\NSCP.INI'
InstallDrive = 'C:'
NSDir = InstallDrive||'\NS40BETA'
InstallDir = NSDir'\Program'
NSVersion = '4.04 (en)'
call RxFuncAdd 'SysLoadFuncs', 'RexxUtil', 'SysLoadFuncs'
call SysLoadFuncs

/* Add ini entries for Netcaster */
call SysIni IniName, 'Netcaster', 'CurrentVersion', NSVersion
call SysIni IniName, 'Netcaster-'||NSVersion, 'Install Directory',NSDir'\Netcast'
/* Add ini entries for Host On-Demand */
call SysIni IniName, '3270', 'CurrentVersion', NSVersion
call SysIni IniName, '3270-'||NSVersion, 'Install Directory',NSDir'\3270'
/* Add ini entries for AOL Instant Messenger */
call SysIni IniName, 'AIM', 'CurrentVersion', NSVersion
call SysIni IniName, 'AIM-'||NSVersion, 'Install Directory',NSDir'\AIM'

/* Add Registry entries for View Source */
call SysIni IniName, 'Registry',
'\HKEY_CLASSES_ROOT\viewsource','URL:View Source'
call SysIni IniName, 'Registry','\HKEY_CLASSES_ROOT\viewsource\shell',0
call SysIni IniName, 'Registry','\HKEY_CLASSES_ROOT\viewsource\shell\open',0
call SysIni IniName, 'Registry','\HKEY_CLASSES_ROOT\viewsource\shell\open\command','C:\OS2\E.EXE'

Now how to use it:

Install Netscape on windows, copy the contents of NETCAST, 3270, and AIM directories to the appropriately named directories under where you installed NETSCAPE:

NETSCAPE\PROGRAM
NETSCAPE\3270
NETSCAPE\NETCAST
NETSCAPE\AIM

Note that these three products are NOT supported, but feel free to try. Note that the AOL pulldown will just launch AIM.EXE in the AIM directory, so you can put anything there.

Once you have added the View Source entry, you can modify the settings for it in the Preferences->Applications.

All these are entries you can add to your PREFS.JS file to do various things. Have fun experimenting:

If we see a web page with Arial, Helvetica, we pick Helvetica if this preference is true
user_pref("os2.arial_pref", false|true);

Specify a wave file for new mail sound. REMEMBER double backslashes!
user_pref("os2.mail.sound","C:\\MMOS2\\SOUNDS\\GOTMAIL.WAV");

Prevents ALL filename mangling when downloading (dots and extension) if set to false
user_pref("os2.replace_dots", true|false );

Turns off URL bar completion if set to false
user_pref("os2.url_completion", true|false );

Causes User Defined Encoding to use default codepage of OS/2 if set to true. On Russian systems, this allows you to see 866 web pages. On default OS/2 systems, you can see 850 pages.
user_pref("os2.use_oem_charset", true|false );

Viewing any language web page in Communicator - If you use Times Roman MT 30 as your font for ALL encodings, you will be able to see stuff in any language.

Chinese and Korean only work on FP 5 or later (I think)

Causing helpers to be launched by the WPS - If you check the application radio button when EDITING (not creating) a helper, but leave the application entry field blank, the item simply gets passed to the Workplace Shell. This can be used to launch Windows helpers with proper settings, as well as just letting the WPS handle all misc types.

I've just noticed that some RSU scripts don't run right and fail with a "message not found" error when using RSUINST.EXE as a helper app in Comm/2 4.04 release...

I've got a workaround - RSU is not included as a helper in Comm/2 by default so follow these steps...

1) In Comm/2, choose Edit->Preferences->Navigator->Applications.
2) Add a new type:
    Description: RSU Install
    extension:   RSU
    MIME Type:   application/rsu
    Application: RSUINST.EXE
   ...and press OK
3) Select the newly added "RSU Install" app. and Press Edit.
4) Clear the Handled By->Application entry field. (remove RSUINST.EXE)
5) Hit OK twice to get out of Preferences.
6) Find RSUINST.EXE (usually in the TCPIP\BIN folder)
7) Open the Properties for RSUINST.EXE and choose the Association page.
8) Enter:
     *.RSU
   ...in the "New name" field and press add.

Earlier it was impossible to convert the addressbook from PMMail to Netscape Communicator for OS/2, but it is possible now, if you follow following procedure.

1. Use PMMACONV by Rolf Lochbuehler (pconv_15.zip in Hobbes Incoming). I just ran it in the X:\SOUTHSDE\TOOLS directory after checking the proper commands with the parameter /h. This produces an address book in html.

2. This html file was converted with a utility MakeLDIF by Dick Goran,to a LDI file that later can be imported to the Netscape Communicator for OS/2 address book. This program is available at Dick Goran's website.

Adding the following line to prefs.js will cause Communicator to report itself as the Windows version. You should only use this if you are locked out of sites that check for the Windows version; leaving it in there all the time will not let people know that you are using OS/2! When you come across a badly written site that checks for the Windows version, be sure to let them know the error of their ways! Note that it does not matter if it is set to true or false, it works the same.

user_pref("os2.emulate.windows", true);

user_pref("mail.use_altmail", true);
user_pref("mail.altmail_dll", "NSMAPI32.DLL");