I don't think text tiles in dcl have a color attribute. Only suggestion I would have at this time, make an image_button. Example in my batch app (see couple of posts back , odxb ...) , rlxbatch.lsp (unfinished routine by the way , just so you know).
Make sure you have only 1 drawing open and SDI = 0. Now when you load & run rlxbatch in the lower right corner you should see MDI in a gray field. This means autocad is in multi-docci mode but with only one drawing open. If you click on this field (an image button) it should turn green and show the text SDI , meaning autocad is in single mode. Click on it again and autocad switches back to MDI. (ok , you can stop clicking now this is getting embarrassing haha) If you try the same with more than 1 drawing open this button turns red , meaning you can't go back to single mode unless you close all but the current drawing.
or put it in a list or edit box but that's only shifting focus , but the color would be white letters on blue
If someone has an other or better way , I'm all ears...
gr. Rlx