function FocusManager(editorManager) {
		function getActiveElement() {
			try {
				return document.activeElement;
			} catch (ex) {
				// IE sometimes fails to get the activeElement when resizing table
				// TODO: Investigate this
				return document.body;
			}
		}

		// We can't store a real range on IE 11 since it gets mutated so we need to use a bookmark object
		// TODO: Move this to a separate range utils class since it's it's logic is present in Selection as well.
		function createBookmark(dom, rng) {
			if (rng && rng.startContainer) {
				// Verify that the range is within the root of the editor
				if (!dom.isChildOf(rng.startContainer, dom.getRoot()) || !dom.isChildOf(rng.endContainer, dom.getRoot())) {
					return;
				}

				return {
					startContainer: rng.startContainer,
					startOffset: rng.startOffset,
					endContainer: rng.endContainer,
					endOffset: rng.endOffset
				};
			}

			return rng;
		}

		function bookmarkToRng(editor, bookmark) {
			var rng;

			if (bookmark.startContainer) {
				rng = editor.getDoc().createRange();
				rng.setStart(bookmark.startContainer, bookmark.startOffset);
				rng.setEnd(bookmark.endContainer, bookmark.endOffset);
			} else {
				rng = bookmark;
			}

			return rng;
		}

		function isUIElement(elm) {
			return !!DOM.getParent(elm, FocusManager.isEditorUIElement);
		}

		function registerEvents(e) {
			var editor = e.editor;

			editor.on('init', function() {
				// Gecko/WebKit has ghost selections in iframes and IE only has one selection per browser tab
				if (editor.inline || Env.ie) {
					// Use the onbeforedeactivate event when available since it works better see #7023
					if ("onbeforedeactivate" in document && Env.ie < 9) {
						editor.dom.bind(editor.getBody(), 'beforedeactivate', function(e) {
							if (e.target != editor.getBody()) {
								return;
							}

							try {
								editor.lastRng = editor.selection.getRng();
							} catch (ex) {
								// IE throws "Unexcpected call to method or property access" some times so lets ignore it
							}
						});
					} else {
						// On other browsers take snapshot on nodechange in inline mode since they have Ghost selections for iframes
						editor.on('nodechange mouseup keyup', function(e) {
							var node = getActiveElement();

							// Only act on manual nodechanges
							if (e.type == 'nodechange' && e.selectionChange) {
								return;
							}

							// IE 11 reports active element as iframe not body of iframe
							if (node && node.id == editor.id + '_ifr') {
								node = editor.getBody();
							}

							if (editor.dom.isChildOf(node, editor.getBody())) {
								editor.lastRng = editor.selection.getRng();
							}
						});
					}

					// Handles the issue with WebKit not retaining selection within inline document
					// If the user releases the mouse out side the body since a mouse up event wont occur on the body
					if (Env.webkit && !selectionChangeHandler) {
						selectionChangeHandler = function() {
							var activeEditor = editorManager.activeEditor;

							if (activeEditor && activeEditor.selection) {
								var rng = activeEditor.selection.getRng();

								// Store when it's non collapsed
								if (rng && !rng.collapsed) {
									editor.lastRng = rng;
								}
							}
						};

						DOM.bind(document, 'selectionchange', selectionChangeHandler);
					}
				}
			});

			editor.on('setcontent', function() {
				editor.lastRng = null;
			});

			// Remove last selection bookmark on mousedown see #6305
			editor.on('mousedown', function() {
				editor.selection.lastFocusBookmark = null;
			});

			editor.on('focusin', function() {
				var focusedEditor = editorManager.focusedEditor, lastRng;

				if (editor.selection.lastFocusBookmark) {
					lastRng = bookmarkToRng(editor, editor.selection.lastFocusBookmark);
					editor.selection.lastFocusBookmark = null;
					editor.selection.setRng(lastRng);
				}

				if (focusedEditor != editor) {
					if (focusedEditor) {
						focusedEditor.fire('blur', {focusedEditor: editor});
					}

					editorManager.setActive(editor);
					editorManager.focusedEditor = editor;
					editor.fire('focus', {blurredEditor: focusedEditor});
					editor.focus(true);
				}

				editor.lastRng = null;
			});

			editor.on('focusout', function() {
				Delay.setEditorTimeout(editor, function() {
					var focusedEditor = editorManager.focusedEditor;

					// Still the same editor the blur was outside any editor UI
					if (!isUIElement(getActiveElement()) && focusedEditor == editor) {
						editor.fire('blur', {focusedEditor: null});
						editorManager.focusedEditor = null;

						// Make sure selection is valid could be invalid if the editor is blured and removed before the timeout occurs
						if (editor.selection) {
							editor.selection.lastFocusBookmark = null;
						}
					}
				});
			});

			// Check if focus is moved to an element outside the active editor by checking if the target node
			// isn't within the body of the activeEditor nor a UI element such as a dialog child control
			if (!documentFocusInHandler) {
				documentFocusInHandler = function(e) {
					var activeEditor = editorManager.activeEditor, target;

					target = e.target;

					if (activeEditor && target.ownerDocument == document) {
						// Check to make sure we have a valid selection don't update the bookmark if it's
						// a focusin to the body of the editor see #7025
						if (activeEditor.selection && target != activeEditor.getBody()) {
							activeEditor.selection.lastFocusBookmark = createBookmark(activeEditor.dom, activeEditor.lastRng);
						}

						// Fire a blur event if the element isn't a UI element
						if (target != document.body && !isUIElement(target) && editorManager.focusedEditor == activeEditor) {
							activeEditor.fire('blur', {focusedEditor: null});
							editorManager.focusedEditor = null;
						}
					}
				};

				DOM.bind(document, 'focusin', documentFocusInHandler);
			}

			// Handle edge case when user starts the selection inside the editor and releases
			// the mouse outside the editor producing a new selection. This weird workaround is needed since
			// Gecko doesn't have the "selectionchange" event we need to do this. Fixes: #6843
			if (editor.inline && !documentMouseUpHandler) {
				documentMouseUpHandler = function(e) {
					var activeEditor = editorManager.activeEditor, dom = activeEditor.dom;

					if (activeEditor.inline && dom && !dom.isChildOf(e.target, activeEditor.getBody())) {
						var rng = activeEditor.selection.getRng();

						if (!rng.collapsed) {
							activeEditor.lastRng = rng;
						}
					}
				};

				DOM.bind(document, 'mouseup', documentMouseUpHandler);
			}
		}

		function unregisterDocumentEvents(e) {
			if (editorManager.focusedEditor == e.editor) {
				editorManager.focusedEditor = null;
			}

			if (!editorManager.activeEditor) {
				DOM.unbind(document, 'selectionchange', selectionChangeHandler);
				DOM.unbind(document, 'focusin', documentFocusInHandler);
				DOM.unbind(document, 'mouseup', documentMouseUpHandler);
				selectionChangeHandler = documentFocusInHandler = documentMouseUpHandler = null;
			}
		}

		editorManager.on('AddEditor', registerEvents);
		editorManager.on('RemoveEditor', unregisterDocumentEvents);
	}
Constructs a new focus manager instance.

@constructor FocusManager
@param {tinymce.EditorManager} editorManager Editor manager instance to handle focus for.