I've simplified the controls for selection boxes (and also slightly changed the color scheme). You no longer have to press plant 2 times!
First, make a box around something and press plant, ctrl c or ctrl x to confirm.
The selection box becomes greyed out, and you can see the highlighted bricks just like in stack mode:

From here, you can just start moving the selection with ghost brick controls.
If it didn't select the right bricks, press cancel brick to go back to the box and edit it:

Just like before, you can start moving the selection with ghost brick controls.
Version 1.3.7• Improved selection box controls
• Improved selection box color scheme
• Align new selection boxes to face the player
• Automatically equip a duplicator when attempting to load a save
• Fixed: Mirror error message not showing after planting
• Fixed: Some saves loading with an incorrect bounding box (again)
Use the automatic updater if you can, otherwise download again from the first page.
If the updater does not show an update, run this command: Updater.checkForUpdates();