diff --git a/vendors/squire/build/squire-raw.js b/vendors/squire/build/squire-raw.js
index cc1640391..8f144c07d 100644
--- a/vendors/squire/build/squire-raw.js
+++ b/vendors/squire/build/squire-raw.js
@@ -17,6 +17,7 @@ const
 	DOCUMENT_FRAGMENT_NODE = 11,     // Node.DOCUMENT_FRAGMENT_NODE,
 	SHOW_ELEMENT = 1,                // NodeFilter.SHOW_ELEMENT,
 	SHOW_TEXT = 4,                   // NodeFilter.SHOW_TEXT,
+	SHOW_ELEMENT_OR_TEXT = 5,
 
 	START_TO_START = 0, // Range.START_TO_START
 	START_TO_END = 1,   // Range.START_TO_END
@@ -1034,7 +1035,7 @@ const
 	},
 
 	newContentWalker = root => createTreeWalker( root,
-		SHOW_TEXT|SHOW_ELEMENT,
+		SHOW_ELEMENT_OR_TEXT,
 		node => node.nodeType === TEXT_NODE ? notWS.test( node.data ) : node.nodeName === 'IMG'
 	),
 
@@ -1206,7 +1207,7 @@ const
 		// Save undo checkpoint and add any links in the preceding section.
 		// Remove any zws so we don't think there's content in an empty
 		// block.
-		self._recordUndoState( range );
+		self._recordUndoState( range, false );
 		if ( self._config.addLinks ) {
 			addLinks( range.startContainer, root, self );
 		}
@@ -1505,7 +1506,7 @@ const
 		while ( isInline( nonInlineParent ) ) {
 			nonInlineParent = nonInlineParent.parentNode;
 		}
-		let walker = createTreeWalker( nonInlineParent, SHOW_TEXT|SHOW_ELEMENT );
+		let walker = createTreeWalker( nonInlineParent, SHOW_ELEMENT_OR_TEXT );
 
 		for ( i = 0, l = children.length; i < l; ++i ) {
 			child = children[i];
@@ -1612,7 +1613,7 @@ const
 		while ( isInline( block ) ) {
 			block = block.parentNode;
 		}
-		walker = createTreeWalker( block, SHOW_ELEMENT|SHOW_TEXT, notWSTextNode );
+		walker = createTreeWalker( block, SHOW_ELEMENT_OR_TEXT, notWSTextNode );
 		walker.currentNode = br;
 		return !!walker.nextNode() ||
 			( isLBIfEmptyBlock && !walker.previousNode() );
@@ -1929,7 +1930,7 @@ let contentWalker,
 TreeWalker.prototype.previousPONode = function () {
 	let current = this.currentNode,
 		root = this.root,
-		nodeType = this.nodeType,
+		nodeType = this.nodeType, // whatToShow?
 		filter = this.filter,
 		node;
 	while ( current ) {
@@ -2405,7 +2406,7 @@ let keyHandlers = {
 	space: ( self, _, range ) => {
 		let node;
 		let root = self._root;
-		self._recordUndoState( range );
+		self._recordUndoState( range, false );
 		if ( self._config.addLinks ) {
 			addLinks( range.startContainer, root, self );
 		}
@@ -2470,6 +2471,123 @@ keyHandlers[ ctrlKey + 'z' ] = mapKeyTo( 'undo' );
 keyHandlers[ 'undo' ] = mapKeyTo( 'undo' );
 keyHandlers[ ctrlKey + 'shift-z' ] = mapKeyTo( 'redo' );
 
+class EditStack extends Array
+{
+	constructor(squire) {
+		super();
+		this.squire = squire;
+		this.index = -1;
+		this.inUndoState = false;
+
+		this.threshold = -1; // -1 means no threshold
+		this.limit = -1; // -1 means no limit
+	}
+
+	clear() {
+		this.index = -1;
+		this.length = 0;
+	}
+
+	stateChanged ( /*canUndo, canRedo*/ ) {
+		this.squire.fireEvent( 'undoStateChange', {
+			canUndo: this.index > 0,
+			canRedo: this.index + 1 < this.length
+		});
+		this.squire.fireEvent( 'input' );
+	}
+
+	docWasChanged () {
+		if ( this.inUndoState ) {
+			this.inUndoState = false;
+			this.stateChanged ( /*true, false*/ );
+		} else
+			this.squire.fireEvent( 'input' );
+	}
+
+	// Leaves bookmark
+	recordUndoState ( range, replace ) {
+		replace = replace !== false && this.inUndoState;
+		// Don't record if we're already in an undo state
+		if ( !this.inUndoState || replace ) {
+			// Advance pointer to new position
+			let undoIndex = this.index;
+			let undoThreshold = this.threshold;
+			let undoLimit = this.limit;
+			let squire = this.squire;
+			let html;
+
+			if ( !replace ) {
+				++undoIndex;
+			}
+			undoIndex = Math.max(0, undoIndex);
+
+			// Truncate stack if longer (i.e. if has been previously undone)
+			this.length = Math.min(undoIndex + 1, this.length);
+
+			// Get data
+			if ( range ) {
+				squire._saveRangeToBookmark( range );
+			}
+			html = squire._getHTML();
+
+			// If this document is above the configured size threshold,
+			// limit the number of saved undo states.
+			// Threshold is in bytes, JS uses 2 bytes per character
+			if ( undoThreshold > -1 && html.length * 2 > undoThreshold
+			 && undoLimit > -1 && undoIndex > undoLimit ) {
+				this.splice( 0, undoIndex - undoLimit );
+			}
+
+			// Save data
+			this[ undoIndex ] = html;
+			this.index = undoIndex;
+			this.inUndoState = true;
+		}
+	}
+
+	saveUndoState ( range ) {
+		let squire = this.squire;
+		if ( range === undefined ) {
+			range = squire.getSelection();
+		}
+		this.recordUndoState( range );
+		squire._getRangeAndRemoveBookmark( range );
+	}
+
+	undo () {
+		let squire = this.squire,
+			undoIndex = this.index - 1;
+		// Sanity check: must not be at beginning of the history stack
+		if ( undoIndex >= 0 || !this.inUndoState ) {
+			// Make sure any changes since last checkpoint are saved.
+			this.recordUndoState( squire.getSelection(), false );
+			this.index = undoIndex;
+			squire._setHTML( this[ undoIndex ] );
+			let range = squire._getRangeAndRemoveBookmark();
+			if ( range ) {
+				squire.setSelection( range );
+			}
+			this.inUndoState = true;
+			this.stateChanged ( /*undoIndex > 0, true*/ );
+		}
+	}
+
+	redo () {
+		// Sanity check: must not be at end of stack and must be in an undo state.
+		let squire = this.squire,
+			undoIndex = this.index + 1;
+		if ( undoIndex < this.length && this.inUndoState ) {
+			this.index = undoIndex;
+			squire._setHTML( this[ undoIndex ] );
+			let range = squire._getRangeAndRemoveBookmark();
+			if ( range ) {
+				squire.setSelection( range );
+			}
+			this.stateChanged ( /*true, undoIndex + 1 < this.length*/ );
+		}
+	}
+}
+
 class Squire
 {
 	constructor (root, config) {
@@ -2501,10 +2619,7 @@ class Squire
 		};
 		this.addEventListener('selectstart', () => this.addEventListener('selectionchange', selectionchange));
 
-		this._undoIndex = -1;
-		this._undoStack = [];
-		this._undoStackLength = 0;
-		this._isInUndoState = false;
+		this.editStack = new EditStack(this);
 		this._ignoreChange = false;
 		this._ignoreAllChanges = false;
 
@@ -2558,10 +2673,6 @@ class Squire
 	setConfig ( config ) {
 		config = mergeObjects({
 			blockTag: 'DIV',
-			undo: {
-				documentSizeThreshold: -1, // -1 means no threshold
-				undoLimit: -1 // -1 means no limit
-			},
 			addLinks: true
 		}, config, true );
 
@@ -2663,24 +2774,6 @@ class Squire
 		return this;
 	}
 
-	destroy () {
-		let events = this._events;
-		let type;
-
-		for ( type in events ) {
-			this.removeEventListener( type );
-		}
-		if ( this._mutation ) {
-			this._mutation.disconnect();
-		}
-		delete this._root.__squire__;
-
-		// Destroy undo stack
-		this._undoIndex = -1;
-		this._undoStack = [];
-		this._undoStackLength = 0;
-	}
-
 	handleEvent ( event ) {
 		this.fireEvent( event.type, event );
 	}
@@ -2849,7 +2942,7 @@ class Squire
 		}
 		let walker = createTreeWalker(
 			range.commonAncestorContainer,
-			SHOW_TEXT|SHOW_ELEMENT,
+			SHOW_ELEMENT_OR_TEXT,
 			node => isNodeContainedInRange( range, node )
 		);
 		let startContainer = range.startContainer;
@@ -3024,121 +3117,29 @@ class Squire
 
 	_docWasChanged () {
 		nodeCategoryCache = new WeakMap();
-		if ( this._ignoreAllChanges ) {
-			return;
+		if ( !this._ignoreAllChanges ) {
+			if ( this._ignoreChange ) {
+				this._ignoreChange = false;
+			} else {
+				this.editStack.docWasChanged();
+			}
 		}
-
-		if ( this._ignoreChange ) {
-			this._ignoreChange = false;
-			return;
-		}
-		if ( this._isInUndoState ) {
-			this._isInUndoState = false;
-			this.fireEvent( 'undoStateChange', {
-				canUndo: true,
-				canRedo: false
-			});
-		}
-		this.fireEvent( 'input' );
 	}
 
-	// Leaves bookmark
 	_recordUndoState ( range, replace ) {
-		// Don't record if we're already in an undo state
-		if ( !this._isInUndoState|| replace ) {
-			// Advance pointer to new position
-			let undoIndex = this._undoIndex;
-			let undoStack = this._undoStack;
-			let undoConfig = this._config.undo;
-			let undoThreshold = undoConfig.documentSizeThreshold;
-			let undoLimit = undoConfig.undoLimit;
-			let html;
-
-			if ( !replace ) {
-				++undoIndex;
-			}
-
-			// Truncate stack if longer (i.e. if has been previously undone)
-			if ( undoIndex < this._undoStackLength ) {
-				undoStack.length = this._undoStackLength = undoIndex;
-			}
-
-			// Get data
-			if ( range ) {
-				this._saveRangeToBookmark( range );
-			}
-			html = this._getHTML();
-
-			// If this document is above the configured size threshold,
-			// limit the number of saved undo states.
-			// Threshold is in bytes, JS uses 2 bytes per character
-			if ( undoThreshold > -1 && html.length * 2 > undoThreshold ) {
-				if ( undoLimit > -1 && undoIndex > undoLimit ) {
-					undoStack.splice( 0, undoIndex - undoLimit );
-					undoIndex = undoLimit;
-					this._undoStackLength = undoLimit;
-				}
-			}
-
-			// Save data
-			undoStack[ undoIndex ] = html;
-			this._undoIndex = undoIndex;
-			++this._undoStackLength;
-			this._isInUndoState = true;
-		}
+		this.editStack.recordUndoState( range, replace );
 	}
 
 	saveUndoState ( range ) {
-		if ( range === undefined ) {
-			range = this.getSelection();
-		}
-		this._recordUndoState( range, this._isInUndoState );
-		this._getRangeAndRemoveBookmark( range );
-
-		return this;
+		this.editStack.saveUndoState( range );
 	}
 
 	undo () {
-		// Sanity check: must not be at beginning of the history stack
-		if ( this._undoIndex !== 0 || !this._isInUndoState ) {
-			// Make sure any changes since last checkpoint are saved.
-			this._recordUndoState( this.getSelection(), false );
-
-			--this._undoIndex;
-			this._setHTML( this._undoStack[ this._undoIndex ] );
-			let range = this._getRangeAndRemoveBookmark();
-			if ( range ) {
-				this.setSelection( range );
-			}
-			this._isInUndoState = true;
-			this.fireEvent( 'undoStateChange', {
-				canUndo: this._undoIndex !== 0,
-				canRedo: true
-			});
-			this.fireEvent( 'input' );
-		}
-		return this;
+		this.editStack.undo();
 	}
 
 	redo () {
-		// Sanity check: must not be at end of stack and must be in an undo
-		// state.
-		let undoIndex = this._undoIndex,
-			undoStackLength = this._undoStackLength;
-		if ( undoIndex + 1 < undoStackLength && this._isInUndoState ) {
-			++this._undoIndex;
-			this._setHTML( this._undoStack[ this._undoIndex ] );
-			let range = this._getRangeAndRemoveBookmark();
-			if ( range ) {
-				this.setSelection( range );
-			}
-			this.fireEvent( 'undoStateChange', {
-				canUndo: true,
-				canRedo: undoIndex + 2 < undoStackLength
-			});
-			this.fireEvent( 'input' );
-		}
-		return this;
+		this.editStack.redo();
 	}
 
 	// --- Inline formatting ---
@@ -3282,7 +3283,7 @@ class Squire
 			// them, and adding other styles is harmless.
 			walker = createTreeWalker(
 				range.commonAncestorContainer,
-				SHOW_TEXT|SHOW_ELEMENT,
+				SHOW_ELEMENT_OR_TEXT,
 				node => ( node.nodeType === TEXT_NODE ||
 							node.nodeName === 'BR' ||
 							node.nodeName === 'IMG'
@@ -3515,7 +3516,7 @@ class Squire
 		}
 
 		// 1. Save undo checkpoint and bookmark selection
-		this._recordUndoState( range, this._isInUndoState );
+		this._recordUndoState( range );
 
 		let root = this._root;
 		let frag;
@@ -3563,7 +3564,7 @@ class Squire
 		}
 
 		// Save undo checkpoint and bookmark selection
-		this._recordUndoState( range, this._isInUndoState );
+		this._recordUndoState( range );
 
 		// Increase list depth
 		let type = list.nodeName;
@@ -3613,7 +3614,7 @@ class Squire
 		}
 
 		// Save undo checkpoint and bookmark selection
-		this._recordUndoState( range, this._isInUndoState );
+		this._recordUndoState( range );
 
 		if ( startLi ) {
 			// Find the new parent list node
@@ -3670,13 +3671,6 @@ class Squire
 		}
 	}
 
-	// --- Keyboard interaction ---
-
-	setKeyHandler ( key, fn ) {
-		this._keyHandlers[ key ] = fn;
-		return this;
-	}
-
 	// --- Get/Set data ---
 
 	_getHTML () {
@@ -3751,10 +3745,7 @@ class Squire
 		fixCursor( root, root );
 
 		// Reset the undo stack
-		this._undoIndex = -1;
-		this._undoStack.length = 0;
-		this._undoStackLength = 0;
-		this._isInUndoState = false;
+		this.editStack.clear();
 
 		// Record undo state
 		let range = this._getRangeAndRemoveBookmark() ||