This is observed from the jira.attlassian.com 4.0 beta 2 release:

When you minimize a "Project Statistics" portlet, you can not tell what is inside the Portlet.

From screen shot example: The Portlet that is minimized shows stats on "Project: Crowd", however there is no way to tell this by looking at it.

• Should minimized portlets act like minimized taskbar items, include the file open in the writeup?

Not shown in the screenshot:

When you change the Background Color to White and minimize the area it appears to disappear. This is because the text is white by default and there is no box around it.
Solution Options

• Do not let the background be the same color as the text (browser overrides of CSS considerations would have to be excluded from this)
• Let user set font color in quick drop down for that box