The GNU/Linux version can be downloaded here.
I've asked David to create a Windows port.
[Edit: and...] The Windows version can be downloaded here.
This new version features:
+ Added a screen that can be used to place custom tiles.
+ It's now possible to double the interface size.
+ Users can now copy and paste rooms, and flip rooms (horizontally and vertically).
+ Levels can now also be exported to XML.
+ The events screen now displays the target tile.
+ It's now possible to sprinkle levels with random decorations.
+ Added a simple help screen.
+ Added two extra guard levels.
+ A LEVELS.BAK file is now being created before saving a level.
+ The application can now immediately display any level on startup.
+ It's now possible to switch between dungeon and palace environments.
* Several aesthetic and interaction improvements.[1]
* Clearing a room now also removes the guard.
* It's now easier to re-use the last used tile.
* The scroll wheel can now also be used for horizontal scrolling.
* Immediately playtesting specific levels now also works with non-default cheat codes.
* Randomize no longer uses - now marked - distorting tiles.
* It's now easier to decrease room numbers on the broken room links screen.
* Fixed the image of one of the palace tiles.
[1] Displays the room under the current room. If there is no room to the left, displays a wall. Better response to the selection of persons. Key repeat on. Less unnecessary screen updates.
Couple of screenshots:



Video:
I'm currently working on adding PoP2 support to apoplexy.