actually i've recently been doing this same kinda thing

and i've found its far quicker to actually plot the entire picture within a memblock rather than messing about with the dot x,y command.
i'll show you the current results
now basically i created my own versions of the Dot, Line, Box and Circle commands which will plot themselves directly into a memblock which is then passed over to the background image - so really almost everything you see is part of the background image, however thanks to professional multiple cameras i can setup the images/bitmaps for the background per camera

it also means no faking windows and such because they can all be created with the seperate cameras.
(this will be alot easier if/when pro gets window instances)
i'm not sure how many windows professional is capable of, so tool windows are managed with seperate memblocks being allowed upto 255/window and 255 camera/program
hopefully that many will never be required, and each one can get memory instensive - but hopefully that isn't a problem for smaller programs ... i mean most will limit themselves to the windows allowed open (i hope)
but you have the main window which takes around 700kb-3mb in memory (depending on the screensize) then you have the multiple windows which also can take around as much.
i have been wondering to save ram and other thing using 3D plains for the 2D stuff like floating bars and such, rather than combineing the images based on position - but i'm pretty sure that doesn't work well with other cameras
right now the mouse is a sprite so it goes over everything as are the dropside menus (^_^)
but its all about how you setup the data really
Tsu'va Oni Ni Jyuuko Fiori Sei Tau!
One block follows the suit ... the whole suit of blocks is the path ... what have you found?