By default, a LookUp selection browser will show 2 columns, Code and Description. In some cases this might not be enough. For example, just having the Code and the Name of an Organization might not suffice if the Organization has offices in multiple Cities. In that case, you can expand the LookUp with a column for City. As your list gets more columns, you might need the popup window to be wider. You can now set this using the ExpandWidth attribute.
Setting the ExpandWidth
In the Editor, go to the LookUps Maintenance and select the LookUp you want to set the ExpandWidth for. You will find this ExpandWidth in the Attributes panel. Set the value (in pixels) and click update.
Once the ExpandWidth is set, the popup window will automatically size to this setting. In this case, when the user wants to select an Organization, it will expand to 700px.