How to DISABLE pull-down menu transparency?

By editing the SkinConfig file of a skin of your choice.

OK. Where do I find the file?

A quick guide for a default system skin - Ferox:

1. Open "SYS:MorphOS/Prefs/Skins/Ferox"
2. Find "SkinConfig" file, right-click on it and choose "Edit"
3. Find MENUTRANSPARENCYLEVEL (should be 25) and change it to 0

If you're using an external skin, you should be able to find it in SYS:Prefs/Skins

If using default skins, I would copy the skin (for example Ferox) dir into SYS:Prefs/Skins directory before editing it. And probably better to rename it too (for example FeroxEdit). Then edit it for your needs and take it in use from system settings. This way you won't lose it in the next MorphOS update.

Thanks a lot!
I was looking in system/prefs/skins whilst the skins are located in system/morphos/prefs/skins
Bit confusing because folder 'morphos' is hidden..