Horizontal/vertical mode indicator not showing for new windows

[JakobRieckh]

I have enabled the window indicators via wm.client.focused.color.indicator: #0000FF to color the window frame depending on whether the window is in horizontal vs vertical mode.

The feature works fine, but only after toggling the mode for the first time with <Super> + <Backspace>. The indicators are missing for newly created windows e.g. starting a new terminal.

Is there a way to enable window indicators also for new windows?