Chris Muller uploaded a new version of Morphic to project The Inbox:
http://source.squeak.org/inbox/Morphic-cmm.1613.mcz

==================== Summary ====================

Name: Morphic-cmm.1613
Author: cmm
Time: 24 December 2019, 8:22:13.600935 pm
UUID: b8603634-08a5-4d7d-9ff9-3cd825e9b1f9
Ancestors: Morphic-mt.1612

When autoEnclose is enabled, and [Backspace] is used to remove an initial opening paren-bracket, also remove the corresponding closing paren-bracket, if present.

=============== Diff against Morphic-mt.1612 ===============

Item was changed:
  ----- Method: Editor>>backspace: (in category 'typing/selecting keys') -----
  backspace: aKeyboardEvent 
  	"Backspace over the last character."
  
  	| startIndex |
  	aKeyboardEvent shiftPressed ifTrue: [^ self backWord: aKeyboardEvent].
  	startIndex := self markIndex +
  				(self hasCaret ifTrue: [0] ifFalse: [1]).
  	startIndex := 1 max: startIndex - 1.
+ 	self class autoEnclose ifTrue: [self checkAndHandleEnclosureDeletionFor: aKeyboardEvent].
- 
  	^ self backTo: startIndex!

Item was added:
+ ----- Method: Editor>>checkAndHandleEnclosureDeletionFor: (in category 'private') -----
+ checkAndHandleEnclosureDeletionFor: aKeyboardEvent 
+ 	| openers closers closerIndex nextChar previousChar |
+ 	openers := '([{'.
+ 	closers := ')]}'.
+ 	previousChar := self text
+ 		at: self startIndex - 1
+ 		ifAbsent: [ $X ].
+ 	nextChar := self text
+ 		at: self startIndex
+ 		ifAbsent: [ $X ].
+ 	closerIndex := closers indexOf: nextChar.
+ 	openers
+ 		at: closerIndex
+ 		ifPresent:
+ 			[ : opener | (opener = previousChar and: [ (closers at: closerIndex) = nextChar ]) ifTrue: [ self forwardDelete: aKeyboardEvent ] ]
+ 		ifAbsent: [ "do nothing" ]!