Comment 2 for bug 1327267

> Why is this happening?

The text toolbar is connected to the desktop so that a selection change (objects selected or deselected) updates its values with the ones of the selection or with the default values (if the selection has no text object).
The other toolbars (at least the ones I have checked) seem to behave the same way, but the main difference is that the text toolbar is also updated when the selection is modified (moved, resized...).