Users in Multi User Picker becomes invisible if the result exceeds the CSS width in IE 8

Here are the following steps on how to reproduce this bug:

1. Create a custom field of 'Multi User Picker' type
2. Create at least 6 - 10 dummy users in User Browser
3. Create a new issue and start to have 2 - 4 users in the Multi User Picker custom field
4. The users will appear right below the Reporter field
   
5. However, in IE 8 (8.0.6001 and 8.0.7600) browser, when you increase the number of users in the Multi User Picker custom field until it exceeds the maximum CSS width limit, the user will somehow become 'invisible':
   

Setting a higher resolution will make the problem go away. Also, using a wider screen or enlarging the IE 8 browser and then press on 'Refresh' button will show all the users.

This problem does not occur any longer starting from JIRA 4.2.x.