[regression] buttons for panels are completely hidden if docked

[rickmastfan67]

I'm guessing this was caused by [4793].

Anyways, the buttons for the panels on the right (when they are permanently docked) are now completely missing unless you minimize the panels and then maximize them. Also, if you close and reopen them, the buttons will still not appear. This is happening with both "expert=false" or "expert=true" set in your preference file and with the "Dynamic buttons in side menus" turned off.
Note: If you un-dock the panel, the buttons will show up properly, but will disappear once again when you re-dock the panel.

Steps to reproduce:

1. Start a version before [4793], say [4789].
2. Go to "Preferences > Display Settings > Look and Feel" and make sure the "Dynamic buttons in side menus" box is un-clicked and then save and exit the preferences.
3. Now, dock a few windows on the right after you have loaded some data. (Layers and Properties as examples; and notice the buttons are always there if you have the "Dynamic buttons in side menus" box un-clicked.)
4. Shutdown [4789].
5. Now startup [4793].
6. Load an *.osm file or download some data from the OSM server.

What happens?
Once the data is loaded, look on the right hand side of the screen and notice that the buttons for "Layers" and "Properties" are now completely missing and not even hovering over the panels will make them show up.

What should happen:
The buttons should show up for the panels.

Repository Root: http://josm.openstreetmap.de/svn
Build-Date: 2012-01-15 02:32:13
Last Changed Author: stoecker
Revision: 4793
Repository UUID: 0c6e7542-c601-0410-84e7-c038aed88b3b
URL: http://josm.openstreetmap.de/svn/trunk
Last Changed Date: 2012-01-14 22:58:41 +0100 (Sat, 14 Jan 2012)
Last Changed Rev: 4793

Identification: JOSM/1.5 (4793 en)
Memory Usage: 132 MB / 2730 MB (47 MB allocated, but free)
Java version: 1.6.0_30, Sun Microsystems Inc., Java HotSpot(TM) 64-Bit Server VM
Operating system: Windows 7
Dataset consistency test: No problems found

Plugin: OpeningHoursEditor (27355)
Plugin: buildings_tools (27355)
Plugin: imageryadjust (27355)
Plugin: licensechange (27400)
Plugin: mapdust (27355)
Plugin: measurement (27289)
Plugin: openstreetbugs (27355)
Plugin: restart (27289)
Plugin: reverter (27393)
Plugin: turnlanes (27355)
Plugin: turnrestrictions (27355)
Plugin: undelete (27395)
Plugin: utilsplugin2 (27421)

[stoecker]

In [4794/josm]:

fix #7267 - side menu buttons missing