As a preview of a forthcoming attraction here's something to look at (comments appreciated) and its an alpha version
CBA Textures are probably one of the most tricky things to make. There are quite a few steps involved. However they are relatively simple. You just need patience. You should craefully read the following procedure. This is one method, there are others that you see documented elsewhere.
You need to obtain the program BMPCONV.exe; this program converts BMP files into MBM file. MBM format (multi bitmap file) is the Symbian graphics format, and is used by the Operating System for System graphics. BMPCONV.exe can be downloaded from Symbian's site and is also found of the Nokia 92x0 SDK's (looks in the Tools Directory). This program runs on a Windows PC. The SDK is available for free via Forum Nokia (by download or on CD).
You then need to create (or obtain from elsewhere) between 1 and 4 BMP files to use as your CBA Textures. They should be 130 x 200 pixels. However the horizontal width (130) is not constant when they are displayed on the 9210 (it changes depending on the text in the CBA), and you may wish to experiment with smaller and or larger widths.
The next step is running BMPCONV.exe to convert the BMP files into 1 MBM files. This can de done via the command like. An easier method is to first create a text file with the commands in it and use the text file as an argument when running BMPCONV.exe
You should place all the graphics and BMPCONV.exe into the same folder. You should then create a new text file in this folder (call in filelist.txt). The contents of this file should be as follows:
The first part specifies the name of the MBM to be created. The following 4 lines specify the graphic file to be included in the MBM file. The first part of the last frour lines 'c24' is a variable describing resolution at which the file should be encoded (the second part is obviously the file name of the graphic you are including in the MBM). You can also use a value of c16 for the resolution (and c4, c8, c12). Use either c16 or c24 for best results. The number stands for bits per pixel.
You should then go to the DOS prompt (or equivalent) and go to the folder in which you have stored BMPCONV.exe, the graphics file and the text file. Once there enter the following:
If you have done everything correctly the following will be displayed:
BMCONV version 103.
Multiple Bitmap store type: File store
Epoc file: anyname.mbm
Bitmap file 1 : yourpic1.BMP
Bitmap file 2 : yourpic2.BMP
Bitmap file 3 : yourpic3.BMP
Bitmap file 4 : yourpic4.BMP
You have created the MBM file and you can now use it as specified in 4.4.1. Remember the file should be named display.mbm and placed in the C:/System/Data/ directory.
As an additional tip you can also change the name of the Textures (as they appear in the Display applet in the control panel) by editing the display.rsc file. However do not use names longer than the existing ones the Display applet will crash.
You may also wish to check this thread out the All About ER6 forums.