I have the levels up & running in the new system, with no .net anywhere to be found, and no windows form crap.
The downside is the amount of pretty simple gui controls that need to be recreated, although, I must admit, it's soooo nice having a known, relatively simple task to crank on.
The new interface is cleaner, faster, and more tweakable and customizable.
The editor itself is faster, more stable, and no more memory issues!!!
So far, the IMGUI supports buttons, 'down buttons' that stay down, hot menu bars that show their contents on mouse over, windows, edit boxes and a swatch grid.
The swatch grid control is used for choosing materials, and is much better and more efficient to work with than the old version I made in .net. For one, since I'm using direct3d and not gdi or forms to draw the textures, I don't need to create .bmp thumbs for every texture in the game anymore, just draw the native .dds at the customizable swatch size.
Also, because I am rendering the swatches, rather than just drawing the thumbnails, I modulate by the diffuse material color to better match how they look in game. Thinking about it, I could add the normal map as well by adding a fake tangent space light when drawing the swatches, too.
The material swatch pane is brought up by mousing over the 'Materials' title bar, and when the mouse is over the pane, the mouse wheel switches swatch pages up & down.
Tomorrow I will add some of the missing triangle & vertex controls, and the scene editor, which will require a tree view.