Descriptive Problem Summary:
When pressing any unbound key while DreamSeeker is focused, the Windows "Default Beep" sound effect plays.

Numbered Steps to Reproduce Problem:
Create a new environment
Create a skin
Make 2 new pane 'windows', one for a map, the other for an output
Add a child to the default window
Set the left/top & right/bottom to either pane
Run
Press a button that's bound (default arrow keys)
Press an unbound button

Code Snippet (if applicable) to Reproduce Problem:
N/A

Expected Results:
No Windows sound effect played, because that's ridiculous.

Actual Results:
The "Default Beep" sound effect is played, for no apparent reason. My guess is it's some type of focusing issue. Do note, this can even happen with some bound keys. It's seemingly random on which key it actually wants to cause noise from pressing.

Does the problem occur:
Every time? Or how often? The noise occurs every time, it just depends on which key it actually wants it to happen with.
In other games? I tested in 3 separate games using a similar configuration.
In other user accounts? Yes
On other computers? Yes (multiple people have notified me of the issue happening to them as well)

When does the problem NOT occur?
When a map element is in the default window, and has focus. It doesn't need to be set as the default map.

Did the problem NOT occur in any earlier versions? If so, what was the last version that worked? (Visit http://www.byond.com/download/build to download old versions for testing.)
Tested builds 494.1135, 508.1287, 511.1348, 512.1386 & 513.1538.

Workarounds:
None that I can think of for this particular issue. At this point I'm going to assume it's something wonky with Windows itself, and not (entirely) BYOND.