I used to be really good at making the simicons. I knew the ins and outs of them, but it's been so long, I've forgotten how to do it. The best way to figure it out is to study different panels, and mess around...
Making icons to open panels is quite easy.
Create an appropriate BMP to be used.
Select an ID for the window you want to open.
Create the XML code.
Put the XML file and the bitmap into a folder named, say, MyIcon, or
add it to an existing icon folder/cab file.
Add the code to your panel.cfg file for the window and the icon gauge.
here's a sample of XML code that I use to toggle a "TCAS" window with the ID=1050
Toggle TCAS Window
1050 (>K:PANEL_ID_TOGGLE)
I save this code as "TCAS_Icon.xml"
I have a folder containing my "special icons" located in my gauge folder
where I put the icons I create/modify. "PDS_ICONS"
In the panel.cfg file, I would add "gaugexx=PDS_ICONS!TCAS_Icon, XX, YY, xx, yy
The window containing the TCAS gauge would have the line "ID=1050". This must
match the number in the XML code "TOGGLE" statement.
Paul