The square appears because the text cannot fit in the space allocated for it. If you move the mouse pointer over the box, a message will appear saying "Note: no space for the text!".
You can get rid of the square by selecting the text item in Web Easy then dragging the bottom-right selection handle to make the text item bigger. In certain circumstances (eg: if your text item includes a list) you may need to make the text item bigger by a few lines to get rid of the little square.