Automatically start application when switching pages

I all,
I wish to start automatically applications when I arrive on a specific page.
Everything was working smoothly until I tried switching desktops.
I have 6 desktops each with 3 pages (horizontals).
I’m using FvwmEvent to deal with the “new_page” event:

[DestroyModuleConfig FvwmEvent* *FvwmEvent: new_page FvwmManagePages
Then in FvwmManagePages I deal with apps to be launched on a particular page/desk

DestroyFunc FvwmManagePages
AddToFunc FvwmManagePages
+ I Exec exec echo "Desktop:" $[desk.n] "Page:" $[page.nx] $[page.ny] | osd_cat -d 1
# if on desk 0 page 1 0 start web browser
+ I PipeRead '[[ $[desk.n] -eq 0 && $[page.nx] -eq 1 && $[page.ny] -eq 0 ]] && echo "FvwmDesk0Page10"'
# if on desk 0 page 2 0 start terms for website dev 
+ I PipeRead '[[ $[desk.n] -eq 0 && $[page.nx] -eq 2 && $[page.ny] -eq 0 ]] && echo "FvwmDesk0Page20"'
# if on desk 1 page 0 0 start Mail
+ I PipeRead '[[ $[desk.n] -eq 1 && $[page.nx] -eq 0 && $[page.ny] -eq 0 ]] && echo "FvwmDesk1Page00"'
# if on desk 1 page 1 0 start IRSSI / RSS
+ I PipeRead '[[ $[desk.n] -eq 1 && $[page.nx] -eq 1 && $[page.ny] -eq 0 ]] && echo "FvwmDesk1Page10"'
[... and so on ... ]

I use bindings to change desk/pages:

# Change page on the desktop with control + up/bottom/right/left
# Up/Down disabled since I use horizontal desktop with 3 pages
Key Right A C GotoPage wrapx wrapy +1p 0p
Key Left A C GotoPage wrapx wrapy -1p 0p

# Change Desktop with  Alt + Up/Down (inverted to match Pager)
Key Up A M GotoDesk -1 0 0 5
Key Down A M GotoDesk 1 0 0 5

# Move direclty to page (Ctrl + PageNum)
Key 1 A C GotoPage 0 0
Key 2 A C GotoPage 1 0
Key 3 A C GotoPage 2 0

# Move directly to desktop (Alt + DeskNum)
Key 1 A M GotoDesk 0 0
#Key 2 A M GotoDesk 0 1
#Key 2 A M GotoDeskAndPage 1 $$[page.nx] $$[page.ny]
Key 3 A M GotoDesk 0 2
Key 4 A M GotoDesk 0 3
Key 5 A M GotoDesk 0 4
Key 6 A M GotoDesk 0 5

If I change desk using GotoDesk it doesn’t start the application.
Example: being on desk 0 pagex 0 pagey 0 if I switch (alt+2 or Alt + ) I end up on the correct desk/page (desk 1 pagex 0 pagey 0) however the application is not started :frowning:
I’ve tried with GotoDeskAndPage using the current pagex/y and it doesn’t work too (same if I fix the desk and page in GotoDeskAndPage).

However on the correct desk if I change page (using Ctrl+1/2/3 or Ctrl + right/left) the application is correctly started as expected

What am I doing wrong?
Shall I write a function that first goes to a specific desk and then goes to a specific page? ( GotoDesk 0 X then GotoPage with previous pagex/y saved )

I can also start this FvwmManagePages function on a new_desktop event … but I was more intend to change background colors or menus with this event