I disabled activating by default in weston.ini and I subscribe for agl-shell-desktop protocol application event. In event handler I do

agl_shell_desktop_set_app_property(agl_shell_desktop, app_id,
                                         AGL_SHELL_DESKTOP_APP_ROLE_POPUP, 640, 180,
                                         0, 0, 640, 720, "HDMI-A-2")
agl_shell_desktop_activate(app_id)

but when application is started, it is displayed as maximized and

Refusing to activate surface role 1, app_id simple-egl

is printed in agl-compositor logs in loop.

This issue about adding support to apply window roles after these have been started, from regular ones, to dialog/pop-up ones. Potentially and vice-versa.