Highlight Dummy_Nets

Select Hilight command
Select the colour you wish to use
In the find filter "Find By Name section"

Set the selection criteria to "Net" and "Name"
Type DUMMY in the Fillin to the right of the ">" then hit the TAB key

All DUMMY nets will be hilighted

Script that will perform the required action

setwindow pcb
trapsize 105
generaledit
hilight
setwindow form.find
FORM find name_type Net
FORM find find_name DUMMY
setwindow pcb
trapsize 110

Oops,

GENERALEDIT isn't recognized in v15.7 What's it do?

Sorry, that script was created using 16.

16 has several application modes which are used for pre-selection (Choose the element to be worked on and then the command) which provide an environment in which commands used frequently in a particular task domain, such as etch editing, are readily accessible from right mouse button pop-up menus, based on a selection set of design elements you have chosen.

General-edit application mode lets you perform editing tasks, including place and route, as well as moving, copying, or mirroring, for example.

Etch-edit application mode customizes your environment to perform etch-editing tasks such as adding and sliding connections, delay tuning, and smoothing cline or cline segment angles, for example.

Comment out, using a "#" sign in the begining of the line or delete the general edit line

Again, sorry if that confused you.

OK, thanks to all of you !