I think in most software when you have 2 buttons together such as OK or Cancel, or Save, or Close etc, then the OK is on the right and Cancel on the left but in C3 this seems to change depending on what action you are doing. For example variables has ok on the left and cancel on the right, whch has caused me a number of times to click cancel instead of ok. There are more instances of this. Please keep it consistant. I know it seems like a small thing but it effects productivity. Being able to fly through the interface is a must.
The same can be said for if you press enter instead of clicking. You expect it to always be OK, but sometimes it cancels instead.