At last the PushPull tool bug where some newly created polygons are flipped which might have bothered you for a long time has been fixed.
The following video shows that some flipped polygons are created in some cases in 2.7.19 and older versions.
From 2.7.20 this issue has been fixed as shown below.
And with 2.7.20 you are able to select multiple elements by holding Shift key as well as Ctrl key. The difference is that holding Ctrl isn't allowed for box selection like Unity's object selection.
The last bug we fixed in this update is that raw html tags were exposed in the tooltip when UModeler package is loaded in a project. This has been fixed in 2.7.20
I hope this update will help you in working with UModeler and have enjoyable 3D Modeling time with UModeler!