I am using 4.0.3a. In the Options menu you will find Preferences and Layout.
Preferences lets you choose "English" or "Metric".
Layout lets you specify the room dimensions in inches or centimeters based on your selection in Preferences.
Well, you chose in preferences what measures you want to
display distances in.
But no matter what you specify for display, you can
enter distances in both metric and imperial measures when e.g. setting room size - you just have to specify the unit of measurement too.
Example: I set Options | preferences to use Units: English, Length format 999.9.
Now things I draw will be shown in inches, decimal form - e.g 6.5 for 6 1/2". I could instead have picked e.g. display format 999' 11 7/8", but I prefer to work with inches in decimal form, since I am used to using numbers in decimal form rather than fractions.
Entering a size, e.g. for layout size (really drawing size) in Options | layout, I can enter just the number 120 for room width, and have that interpreted as 120".
But I can also enter room width 10' 6", room width is set to 10' 6" (and the Options | Layout dialog will automatically show 126" next time I look). Or I can enter 1020mm, or 350cm, or 4.2m.
If I
don't add ' or " or cm or mm or m, then whatever number I enter is interpreted as either inches or centimeters, depending on whether I set units to English or Metric.
Smile,
Stein