Styles for Save-wiki button change in modal

[Vayu Asura]

I want to have a custom save-wiki button within a modal.

When I transclude {{$:/core/ui/Buttons/save-wiki}} in a tiddler the button is displayed like on the sidebar with the image, invisible outline and changing color

When I put it into parameter of a modal message it is displayed as a grey empty button without image:

<$button message=tm-modal param="$:/core/ui/Buttons/save-wiki" >pop save button up
</$button>

If I put some text into system tiddler it is case-red according to "tc-dirty-indicator" class so that's retained.

Why are others canceled?