diff --git a/widget/src/cocoa/nsFilePicker.mm b/widget/src/cocoa/nsFilePicker.mm
index 3ad5e856a96..fa2a615f4da 100644
--- a/widget/src/cocoa/nsFilePicker.mm
+++ b/widget/src/cocoa/nsFilePicker.mm
@@ -452,60 +452,41 @@ nsFilePicker::PutLocalFile(const nsString& inTitle, const nsString& inDefaultNam
   NS_OBJC_END_TRY_ABORT_BLOCK_RETURN(0);
 }
 
-// Take the list of file types (in a nice win32-specific format) and fills up
-// an NSArray of them for the Open Panel.  Note: Will return nil if we should allow
-// all file types.
+// Returns the current filter list in a format accepted by NSOpenPanel.
+// Returns nil if no filter currently apply.
 NSArray *
 nsFilePicker::GenerateFilterList()
 {
   NS_OBJC_BEGIN_TRY_ABORT_BLOCK_NIL;
 
-  NSArray *filterArray = nil;
-  if (mFilters.Length() > 0) {
-    // Set up our filter string
-    NSMutableString *giantFilterString = [[[NSMutableString alloc] initWithString:@""] autorelease];
-
-    // Loop through each of the filter strings
-    for (PRUint32 loop = 0; loop < mFilters.Length(); loop++) {
-      const nsString& filterWide = mFilters[loop];
-
-      // separate individual filters
-      if ([giantFilterString length] > 0)
-        [giantFilterString appendString:[NSString stringWithString:@";"]];
-
-      // handle special case filters
-      if (filterWide.Equals(NS_LITERAL_STRING("*"))) {
-        // if we'll allow all files, we won't bother parsing all other
-        // file types. just return early.
-        return nil;
-      }
-      else if (filterWide.Equals(NS_LITERAL_STRING("..apps"))) {
-        // this magic filter means that we should enable app bundles.
-        // translate it into a usable filter, and continue looping through 
-        // other filters.
-        [giantFilterString appendString:@"*.app"];
-        continue;
-      }
-      
-      if (filterWide.Length() > 0)
-        [giantFilterString appendString:[NSString stringWithCharacters:filterWide.get() length:filterWide.Length()]];
-    }
-    
-    // Now we clean stuff up.  Get rid of white spaces, "*"'s, and the odd period or two.
-    NSCharacterSet *aSet = [NSCharacterSet characterSetWithCharactersInString:[NSString stringWithString:@". *"]];
-    NSRange aRange = [giantFilterString rangeOfCharacterFromSet:aSet];
-    while (aRange.length) {
-      [giantFilterString replaceCharactersInRange:aRange withString:@""];
-      aRange = [giantFilterString rangeOfCharacterFromSet:aSet];
-    }   
-    // OK, if string isn't empty we'll make a new filter list
-    if ([giantFilterString length] > 0) {
-      // every time we find a semicolon, we've found a new filter.
-      // components SeparatedByString should do that for us.
-      filterArray = [[[NSArray alloc] initWithArray:[giantFilterString componentsSeparatedByString:@";"]] autorelease];
-    }
+  if (mFilters.Length() <= (PRUint32)mSelectedTypeIndex) {
+    return nil;
   }
-  return filterArray;
+
+  const nsString& filterWide = mFilters[mSelectedTypeIndex];
+  if (!filterWide.Length()) {
+    return nil;
+  }
+
+  if (filterWide.Equals(NS_LITERAL_STRING("*"))) {
+    return nil;
+  }
+
+  // The extensions in filterWide are in the format "*.ext" but are expected
+  // in the format "ext" by NSOpenPanel. So we need to filter some characters.
+  NSMutableString* filterString = [[[NSMutableString alloc] initWithString:
+                                    [NSString stringWithCharacters:filterWide.get()
+				              length:filterWide.Length()]] autorelease];
+  NSCharacterSet *set = [NSCharacterSet characterSetWithCharactersInString:
+                          [NSString stringWithString:@". *"]];
+  NSRange range = [filterString rangeOfCharacterFromSet:set];
+  while (range.length) {
+    [filterString replaceCharactersInRange:range withString:@""];
+    range = [filterString rangeOfCharacterFromSet:set];
+  }
+
+  return [[[NSArray alloc] initWithArray:
+           [filterString componentsSeparatedByString:@";"]] autorelease];
 
   NS_OBJC_END_TRY_ABORT_BLOCK_NIL;
 }
@@ -597,7 +578,12 @@ NS_IMETHODIMP nsFilePicker::SetDefaultExtension(const nsAString& aExtension)
 NS_IMETHODIMP
 nsFilePicker::AppendFilter(const nsAString& aTitle, const nsAString& aFilter)
 {
-  mFilters.AppendElement(aFilter);
+  // "..apps" has to be translated with native executable extensions.
+  if (aFilter.EqualsLiteral("..apps")) {
+    mFilters.AppendElement(NS_LITERAL_STRING("*.app"));
+  } else {
+    mFilters.AppendElement(aFilter);
+  }
   mTitles.AppendElement(aTitle);
   
   return NS_OK;