The AutoCAD .net/ObjectARX APIs have a handy feature called the pick first selection.

Dimension Metal Curves Using a Jig from benkoshy on Vimeo.

I can’t say it any better than what’s said here. It’s masterfully explained and brilliantly clear with .gifs to illustrate the concept. Would highly recommend you take a look, especially if you are writing complex multi-threaded applications.

You might not know this but I have a part time job, at the golf shop. One of my duties involves: stacking the shelves full of products.

Binding Basics: Unfortunately this note will not be for raw beginners with no understanding of WPF.

Explanation without code

There seems to be a lot of confusion with folks about the difference between using the AutoCAD .net API vs the COM Interop API. They both hope to do the same things, but via different ways. Given a choice, I’d always recommend using the .net API because it is much more powerful. Or if you are familiar with C++ then go for ObjectARX API which gives you immense power. You may think that using .net API obviates the need to manage resources - but you’d be wrong: the .net API is simply a wrapper to the underlying unmanaged types. You have to explicitly use transactions or you have to otherwise explicitly dispose of objects after you’ve finished using them. Nevertheless, the .net API is still very good to use in certain instances.