See http://www.netbeans.org/servlets/ReadMsg?msgId=158590&listName=nbui

I'm filing bugs for each module that creates one of the workspaces listed 
in the e-mail.

Core creates the Editing workspace and the Running workspace.  
The main usability problem in the Editing workspace is that the editor window
by default takes up the full height, so when the output window is displayed,
the bottom half of the editor window is obscured and you have to scroll to
see its contents; the editor window should only extend down to where the output
window will appear.  Furthermore, the explorer area is too narrow; it's width
should be increated from 25% to 35% to reduce clipping of nodes when displaying
"deep" source package hierarchies (such as those used by NetBeans source code:-)

Here's the relevant sections to this bug from the e-mail:
NOTE
1.  Widths and heights of adjoining windows should always be adjusted so as to
    avoid the appearance of horizontal or vertical scrollbars on the desktop.

NOTE
2.  In MDI mode and non-MDI mode, the "desktop" is assumed to start just below
    the main toolbar.

Editing Workspace:

1. Explorer + Properties: On the left hand side of the desktop.  Stretches from
   the top to the bottom of the desktop, and are attached/dominant in MDI.
   Takes up about 35% of the desktop's width.  Displayed by default.

2. Source Editor: When opened, its upper right hand corner is aligned with the
   upper right hand corner of the desktop.  It takes up the remainder of the
   desktop's width, and 75% of the height.  Not attached in MDI.  Not displayed
   until needed.

3. Output Window: On the bottom of the desktop.  Stretches from the right side
   of the Explorer to the right side of the desktop.  Attached in MDI, but not
   dominant.  Takes up about 25% of the height.  Not displayed until needed.


Running Workspace:

1.  Execution Window: On the left hand side of the desktop.  Stretches from the
    top of the desktop to the top of the Output Window.  Attached to the
    left-hand side of the desktop in MDI.  Takes up about 35% of the width.
    Displayed by default.

2.  Output Window: On the bottom of the deskop.  Stretches across the desktop,
    and is dominant in MDI.  Takes up about 40% of the desktop's height.

3.  Source Editor: When opened, its upper right hand corner is aligned with the
    desktop's upper right-hand corner.  It takes up the remaining space on the
    desktop.  Not displayed until needed.  Not attached in MDI.

Justification: The Source Editor is now the same width in this window as in the
Editing and Debugging Workspaces.

I've marked this bug a P2 since as a -usability- bug it rates higher;
I would have otherwise prioritized it at P3.