I work on a laptop a lot. To maximise drawing area I only have one horizontal toolbar line, where the InfoBar goes. To its left is a short toolbar with line-width, feathering and zoom drop-downs. Like this...

Click image for larger version.  Name: Xara toolbars.jpg  Views: 287  Size: 16.0 KB  ID: 113880 (1600 pixels long, so you'll have to click to see it)

The rest of the width is plenty for every InfoBar except the Text one. Notice the Text InfoBar is partly off-screen? I have to float it each time I wish to access the right hand options, include the Advanced Text bar.

As you have found a way to split the Text InfoBar into two, could it be split into three? I would suggest everything up to Fully Justify on the main InfoBar, followed by two buttons like Super- and Subscript that toggle the other two bars. The second one would be the Advanced Text bar we have, but the first one could toggle a Format Text toolbar holding the rest.

By default the Format Text InfoBar would appear after the Text InfoBar. For most people the only difference would be that the Advanced Text button would be more central. This would give a Text Infobar more similar in length to the others, making better use of precious screen space. The two additional text bars could float or be docked on a separate line (which would only appear when needed).