Bug 514494 - Make the Windows XP save as filepicker change the file's extension when the filter is changed. r=jimm, sr=vlad

widget/public/nsIFilePicker.idl

@@ -96,7 +96,8 @@ interface nsIFilePicker : nsISupports
                     in AString filter);
 
  /**
-  * The filename that should be suggested to the user as a default.
+  * The filename that should be suggested to the user as a default. This should
+  * include the extension.
   *
   * @throws NS_ERROR_FAILURE on attempts to get
   */

widget/src/windows/nsFilePicker.cpp

@@ -209,6 +209,8 @@ NS_IMETHODIMP nsFilePicker::ShowW(PRInt16 *aReturnVal)
 
     ofn.Flags = OFN_NOCHANGEDIR | OFN_SHAREAWARE | OFN_LONGNAMES | OFN_OVERWRITEPROMPT | OFN_HIDEREADONLY | OFN_PATHMUSTEXIST;
 
+    PRInt32 extIndex = mDefault.RFind(".");
+
     if (!mDefaultExtension.IsEmpty()) {
       ofn.lpstrDefExt = mDefaultExtension.get();
     }
@@ -216,7 +218,6 @@ NS_IMETHODIMP nsFilePicker::ShowW(PRInt16 *aReturnVal)
       // Get file extension from suggested filename
       //  to detect if we are saving an html file
       //XXX: nsIFile SHOULD HAVE A GetExtension() METHOD!
-      PRInt32 extIndex = mDefault.RFind(".");
       if ( extIndex >= 0) {
         nsAutoString ext;
         mDefault.Right(ext, mDefault.Length() - extIndex);
@@ -260,6 +261,12 @@ NS_IMETHODIMP nsFilePicker::ShowW(PRInt16 *aReturnVal)
             StringEndsWith(ext, NS_LITERAL_CSTRING(".url")))
           ofn.Flags |= OFN_NODEREFERENCELINKS;
 
+        // The save-as filepicker on XP doesn't appreciate the default filename
+        // having an extension. Vista and up don't mind either way. If
+        // lpstrDefExt is already defined, strip the .ext from the file name.
+        if (ofn.lpstrDefExt && extIndex >= 0 && extIndex < FILE_BUFFER_SIZE)
+          fileBuffer[extIndex] = '\0';
+
         result = ::GetSaveFileNameW(&ofn);
         if (!result) {
           // Error, find out what kind.