A quick update:
I have added a few new features and taken some suggestions on board.
New features:
Textures-Objects can be textured and the texture can be scaled and scrolled.
Rotation-Now works a little better.
Scale-Also works now for most types of object.
Grid-Has been added which scales automatically depending on zoom level (no "snap to grid" as yet). EDIT: Snap to Grid Added
Parent/Child Mode-To edit my new multi-layered objects.
Box-Is now a multi-layered object (sides of the box can be edited/textured/deleted indipendently).
Room-Is a new multi-layered object (sides can be edited as with box but are only visible from inside where boxes are visible inside and out).
Centre View-User can select a point on an object/space to centre the camera view upon.
Import-Now gives the user the option to import any of the 3 types of object from the "Import" dialogue.
In progress:
Export-I am working on the export function.
View-Various new view modes in progress.
Light mapping-This is the next big issue after Export.
EDIT: Group-To create multi-layered objects
I'll post this version of the "Demo" once I have Export working I guess...