The assembly editor menu has several options and tools to assist you during the creation of new things.
View -> Axes
Use this option to display the x,y and z axes on top of the 3D view.
View -> Ground
This option controls the display of the ground plane ( y = 0 ).
Commands -> Interactive Subpart Editor
The interactive subpart editor allows you to manipulate the position, rotation, scale and origin of the subparts with immediate visual feedback. If you leave the dialog box with "OK", BW Tools will write the changes into your assembly text. Please observe that this tool is rather insensitive to the neat formatting of your text. In other words, it will simply add the changes to the code without preserving any formatting.
Commands -> Open/Close Controller
If your thing has dynamic parts (i.e. has a CANBEOPENED statement and POS_OPEN etc. definitions), you can use this tool to preview the open/close activity.
Commands -> Set Background Color
Allows you to change the background color of the 3D view.