Sebastian (or anybody else!),
Could you describe what you did to enable full Intellisense support?
In the following sample code from the ArcGIS help system, adding a dot after df shows "No Completions" instead of the properties and functions of dataframes.
Thanks
import arcpy
mxd = arcpy.mapping.MapDocument(r"C:\Project\Project.mxd")
for df in arcpy.mapping.ListDataFrames(mxd, "t*"😞
if df.name.lower == "transportation":
df.scale = 24000
df.rotation = 5.5
mxd.saveACopy(r"C:\Project\Project2.mxd")
del mxd