I have another workaround for this problem that worked well for me. The process is to replace the bitmap directly in the PCF file. All of these steps are done in Windows and NOT PENG.

- MAKE A BACKUP COPY OF YOUR CURRENT PCF!!!

- Create a new file folder somewhere in Windows.

- Select your current PCF file in Windows Explorer, then Shift-right-click and do Open-With and select PKZip or your favorite unzipper.

- Extract the files into that folder you created (leave PKZip open).

- Figure out which bitmap_id is the file you need to replace (by opening in Paint or using Thumbnail view).

- Copy the replacement bitmap into the bitmaps sub-folder, giving it the same name as the old one.

- Back in PKZip, select Compress->Add Files and on the window it opens do:
a) Preferences: Relative Path, Include Subdirectories (Recurse), NOT-read-only.
b) Add Options: Update Files
c) Click on the bitmaps directory and do "Add Directory".
d) Select OK
e) For the recursive top-level, select the folder you created (one above bitmaps) and select OK.

- After if finishes the "compression", verify that the date of the bitmap you replaced is different than the other file dates. Also, if there are extra files in the compression, such as the Bitmaps directory itself, or the Thumbnails system file, etc. DELETE THEM.

You're finished. (After writing this out, it sounds more complicated than it is.)

It's also possible to create a PCF directly, without using the Update method. The trick there is to get the Comment right.
Barry