If FireFox is set as your default browser, openURL
doesn't properly open the browser... The browser
opens, but stays at the home page.  In NetBeans,
you see the error:
org.netbeans.modules.extbrowser.NbBrowserException:
DdeConnect errno >400A< when connecting to server
IEXPLORE, topic WWW_Activate. 


Here's a patch (from the release35 code) to
extbrowser that allows it to work with FIREFOX. 
It was a fairly simple matter of adding FIREFOX
every place that
I saw other browsers listed, and adding a constant
for FIREFOX in WinWebBrowser.

Of course, the patch will be different in the
trunk (the trunk doesn't seem to use the full path
to the executable anymore, for one thing) but this
should give you an idea of what needs to be done.



Index:
src/org/netbeans/modules/extbrowser/BrowserPropertyEditor.java
===================================================================
RCS file:
/cvs/extbrowser/src/org/netbeans/modules/extbrowser/Attic/BrowserPropertyEditor.java,v
retrieving revision 1.5
diff -u -r1.5 BrowserPropertyEditor.java
---
src/org/netbeans/modules/extbrowser/BrowserPropertyEditor.java
     2 Jan 2002 18:04:25 -0000    1.5
+++
src/org/netbeans/modules/extbrowser/BrowserPropertyEditor.java
     11 Aug 2004 13:50:21 -0000
@@ -30,7 +30,7 @@
             throw new IllegalArgumentException ();

         if (str.equals(WinWebBrowser.IEXPLORE) ||
str.equals(WinWebBrowser.NETSCAPE) ||
-            str.equals(WinWebBrowser.NETSCAPE6)
|| str.equals(WinWebBrowser.MOZILLA))
+            str.equals(WinWebBrowser.NETSCAPE6)
|| str.equals(WinWebBrowser.MOZILLA) ||
str.equals(WinWebBrowser.FIREFOX))
             setValue (str);

         if (str.equals (NbBundle.getMessage
(BrowserPropertyEditor.class,
"LBL_SystemDefaultBrowser")))
@@ -45,6 +45,7 @@
             WinWebBrowser.IEXPLORE,
             WinWebBrowser.NETSCAPE,
             WinWebBrowser.NETSCAPE6,
+            WinWebBrowser.FIREFOX,
             WinWebBrowser.MOZILLA
         };
         return tags;
Index:
src/org/netbeans/modules/extbrowser/NbDdeBrowserImpl.java
===================================================================
RCS file:
/cvs/extbrowser/src/org/netbeans/modules/extbrowser/NbDdeBrowserImpl.java,v
retrieving revision 1.25
diff -u -r1.25 NbDdeBrowserImpl.java
---
src/org/netbeans/modules/extbrowser/NbDdeBrowserImpl.java
  31 Oct 2002 14:45:35 -0000      1.25
+++
src/org/netbeans/modules/extbrowser/NbDdeBrowserImpl.java
  11 Aug 2004 13:50:21 -0000
@@ -214,6 +214,9 @@
                 if (cmd.toUpperCase ().indexOf
(WinWebBrowser.NETSCAPE) >= 0)
                     return WinWebBrowser.NETSCAPE;

+                if (cmd.toUpperCase ().indexOf
(WinWebBrowser.FIREFOX) >= 0)
+                    return WinWebBrowser.FIREFOX;
+
                 if (cmd.toUpperCase ().indexOf
(WinWebBrowser.MOZILLA) >= 0)
                     return WinWebBrowser.MOZILLA;
             }
Index:
src/org/netbeans/modules/extbrowser/WinWebBrowser.java
===================================================================
RCS file:
/cvs/extbrowser/src/org/netbeans/modules/extbrowser/WinWebBrowser.java,v
retrieving revision 1.17
diff -u -r1.17 WinWebBrowser.java
---
src/org/netbeans/modules/extbrowser/WinWebBrowser.java
     31 Oct 2002 14:45:42 -0000      1.17
+++
src/org/netbeans/modules/extbrowser/WinWebBrowser.java
     11 Aug 2004 13:50:21 -0000
@@ -36,6 +36,8 @@
     public static final String IEXPLORE =
"IEXPLORE";   // NOI18N
     /** Name of DDE server corresponding to
Mozilla */
     public static final String MOZILLA  =
"MOZILLA";    // NOI18N
+    /** Name of DDE server corresponding to
FireFox  */
+    public static final String FIREFOX  =
"FIREFOX";    // NOI18N
     /** Name of DDE server corresponding to
Netscape 6.x */
     public static final String NETSCAPE6 =
"NETSCAPE6";   // NOI18N

@@ -136,6 +138,8 @@
         catch (NbBrowserException e) {
             if (WinWebBrowser.IEXPLORE.equals
(getDDEServer ()))
                 b = "C:\\Program Files\\Internet
Explorer\\iexplore.exe";     // NOI18N
+            else if (WinWebBrowser.FIREFOX.equals
(getDDEServer ()))
+                b = "C:\\Program Files\\Mozilla
Firefox\\firefox.exe";     // NOI18N
             else if (WinWebBrowser.MOZILLA.equals
(getDDEServer ()))
                 b = "C:\\Program
Files\\Mozilla.org\\Mozilla\\mozilla.exe";     //
NOI18N
             else if
(WinWebBrowser.NETSCAPE.equals (getDDEServer ()))