Here this example showed garbage when the switch widget was changed
```sh
yad --form --field=switch:SW TRUE --field=check:CHK TRUE --changed-action='echo 3:' --field=changes
```
To fix this issue I changed the callback according to the gobject signature https://docs.gtk.org/gobject/signal.Object.notify.html.

...key press when no image is loaded

Runs after image file is selected via gtk_file_chooser_dialog
yad --picture --file-op --image-changed="echo %s

now it is in common section and works in html and picture dialogs too
this option is required now to add open action in popup menu of html dialog

add form switch

add form switch

add form switch