Control the width of a drop down list in a SharePoint New or Edit form
If you have a lookup field in one list and the display field (ex. title) is long, chances are the title is truncated and only the first part is visible.
You can fix this without using SPD or InfoPath by utilizing the content editor web part (CEWP). Each element on the form has its own style and its own ID or class as rendered in the browser. You can use the Developer Tools in MSIE or FireBug in FireFox to find out the ID of the drop down control, then add a CEWP to the Edit and New forms of the list.
On the list tab, in the Customize list group, use the Form Web Parts and add a CEWP to the default edit and new forms. Edit the CEWP html source and add a style specifying the ID you got from developer tools or Firebug and set width to 100% for full width. Save the page and try it. You can even maximize the Silverlight window if the text is very long.