Well, John, you're really tweaking TextMaker for all it's worth!
But this also works:
Right-click the picture, select "Picture properties...", go to tab "Picture" and click "More...". Then check "Mix with Colour" and choose the colour you want (or define a new one). NB: This will only work as desired if the white background of the picture has been made transparent before; otherwise, the white will take the colour too.