I've created an unordered list with list elements to use as a nav menu. The display type of the list elements has been set to inline-block via css to flow the list horizontal. But, Dreamweaver CS6 Design View displays the list elements vertical. When viewed in various browsers the list elements are horizontal as expected.
If you want to develop good working habits in DW, go to View > Style Rendering > Turn off Display Styles.
Turning off styles will force you to ignore what you see in Design View and pay closer attention to your code. This will not effect your site in Live View or Preview.
Why doesn't Dreamweaver CS6 V12.2 Display inline-block list elements correctly? I'm of the opinion that Design View was built to support table based layouts, and from an engineering perspective, I would imagine it's been a real beast to try and adapt to accurately represent web standards based layouts.
As Nancy said, focusing on the code helps me to better structure my layouts, and helps me to pinpoint trouble spots. Live View and Preview in a browser are also helpful, but with more complex layouts, a good CSS Editor will save you a lot of time.