Remove Blockly.removeAllRanges and replace it with calls to add/remove

css to mark text as unselectable instead.  I can't prove this is
significantly faster with numbers since the call to setup the time out
costs ~.1ms and the call when the timer fires is ~.05.  This happens on almost
every mouse event though.  Plus, it seems to remove a flicker of highlighting when
frames are skipped and keeps scrolling via the scrollbar from highlighting.

core/block_svg.js

@@ -488,6 +488,7 @@ Blockly.BlockSvg.prototype.onMouseDown_ = function(e) {
     e.stopPropagation();
     return;
   }
+  Blockly.setPageSelectable(false);
   this.workspace.markFocused();
   // Update Blockly's knowledge of its own location.
   Blockly.svgResize(this.workspace);
@@ -508,7 +509,6 @@ Blockly.BlockSvg.prototype.onMouseDown_ = function(e) {
       Blockly.Events.setGroup(true);
     }
     // Left-click (or middle click)
-    Blockly.removeAllRanges();
     Blockly.Css.setCursor(Blockly.Css.Cursor.CLOSED);
 
     this.dragStartXY_ = this.getRelativeToSurfaceXY();
@@ -543,6 +543,7 @@ Blockly.BlockSvg.prototype.onMouseDown_ = function(e) {
  * @private
  */
 Blockly.BlockSvg.prototype.onMouseUp_ = function(e) {
+  Blockly.setPageSelectable(true);
   Blockly.terminateDrag_();
   if (Blockly.selected && Blockly.highlightedConnection_) {
     // Connect two blocks together.
@@ -786,7 +787,6 @@ Blockly.BlockSvg.prototype.onMouseMove_ = function(e) {
     e.stopPropagation();
     return;
   }
-  Blockly.removeAllRanges();
 
   var oldXY = this.getRelativeToSurfaceXY();
   var newXY = this.workspace.moveDrag(e);

core/blockly.js

@@ -170,7 +170,7 @@ Blockly.onMouseUp_ = function(e) {
   var workspace = Blockly.getMainWorkspace();
   Blockly.Css.setCursor(Blockly.Css.Cursor.OPEN);
   workspace.isScrolling = false;
-
+  Blockly.setPageSelectable(true);
   // Unbind the touch event if it exists.
   if (Blockly.onTouchUpWrapper_) {
     Blockly.unbindEvent_(Blockly.onTouchUpWrapper_);
@@ -193,7 +193,6 @@ Blockly.onMouseMove_ = function(e) {
   }
   var workspace = Blockly.getMainWorkspace();
   if (workspace.isScrolling) {
-    Blockly.removeAllRanges();
     var dx = e.clientX - workspace.startDragMouseX;
     var dy = e.clientY - workspace.startDragMouseY;
     var metrics = workspace.startDragMetrics;

core/css.js

@@ -143,6 +143,13 @@ Blockly.Css.CONTENT = [
     'z-index: 999;',
   '}',
 
+  '.blocklyNonSelectable {',
+    'user-select: none;',
+    '-moz-user-select: none;',
+    '-webkit-user-select: none;',
+    '-ms-user-select: none;',
+  '}',
+
   '.blocklyTooltipDiv {',
     'background-color: #ffffc7;',
     'border: 1px solid #ddc;',

core/flyout.js

@@ -536,7 +536,6 @@ Blockly.Flyout.prototype.blockMouseDown_ = function(block) {
       block.showContextMenu_(e);
     } else {
       // Left-click (or middle click)
-      Blockly.removeAllRanges();
       Blockly.Css.setCursor(Blockly.Css.Cursor.CLOSED);
       // Record the current mouse position.
       Blockly.Flyout.startDownEvent_ = e;
@@ -606,7 +605,6 @@ Blockly.Flyout.prototype.onMouseMoveBlock_ = function(e) {
     e.stopPropagation();
     return;
   }
-  Blockly.removeAllRanges();
   var dx = e.clientX - Blockly.Flyout.startDownEvent_.clientX;
   var dy = e.clientY - Blockly.Flyout.startDownEvent_.clientY;
   // Still dragging within the sticky DRAG_RADIUS.

core/scrollbar.js

@@ -442,6 +442,7 @@ Blockly.Scrollbar.prototype.onMouseDownKnob_ = function(e) {
     e.stopPropagation();
     return;
   }
+  Blockly.setPageSelectable(false);
   // Look up the current translation and record it.
   this.startDragKnob = parseFloat(
       this.svgKnob_.getAttribute(this.horizontal_ ? 'x' : 'y'));
@@ -474,7 +475,7 @@ Blockly.Scrollbar.prototype.onMouseMoveKnob_ = function(e) {
  * @private
  */
 Blockly.Scrollbar.prototype.onMouseUpKnob_ = function() {
-  Blockly.removeAllRanges();
+  Blockly.setPageSelectable(true);
   Blockly.hideChaff(true);
   if (Blockly.Scrollbar.onMouseUpWrapper_) {
     Blockly.unbindEvent_(Blockly.Scrollbar.onMouseUpWrapper_);

core/toolbox.js

@@ -390,7 +390,6 @@ Blockly.Toolbox.TreeControl.prototype.createNode = function(opt_html) {
  * @override
  */
 Blockly.Toolbox.TreeControl.prototype.setSelectedItem = function(node) {
-  Blockly.removeAllRanges();
   var toolbox = this.toolbox_;
   if (node == this.selectedItem_ || node == toolbox.tree_) {
     return;

core/utils.js

@@ -347,23 +347,16 @@ Blockly.createSvgElement = function(name, attrs, parent, opt_workspace) {
 };
 
 /**
- * Deselect any selections on the webpage.
- * Chrome will select text outside the SVG when double-clicking.
- * Deselect this text, so that it doesn't mess up any subsequent drag.
+ * Set css classes to allow/disallow the browser from selecting/highlighting
+ * text, etc. on the page.
+ * @param {boolean} selectable Whether elements on the page can be selected.
  */
-Blockly.removeAllRanges = function() {
-  if (window.getSelection) {
-    setTimeout(function() {
-        try {
-          var selection = window.getSelection();
-          if (!selection.isCollapsed) {
-            selection.removeAllRanges();
-          }
-        } catch (e) {
-          // MSIE throws 'error 800a025e' here.
-        }
-      }, 0);
-  }
+Blockly.setPageSelectable = function(selectable) {
+    if (selectable) {
+      Blockly.removeClass_(document.body, 'blocklyNonSelectable');
+    } else {
+      Blockly.addClass_(document.body, 'blocklyNonSelectable');
+    }
 };
 
 /**

core/workspace_svg.js

@@ -571,6 +571,7 @@ Blockly.WorkspaceSvg.prototype.isDeleteArea = function(e) {
  */
 Blockly.WorkspaceSvg.prototype.onMouseDown_ = function(e) {
   this.markFocused();
+  Blockly.setPageSelectable(false);
   if (Blockly.isTargetInput_(e)) {
     return;
   }
@@ -588,7 +589,6 @@ Blockly.WorkspaceSvg.prototype.onMouseDown_ = function(e) {
     // Right-click.
     this.showContextMenu_(e);
   } else if (this.scrollbar) {
-    Blockly.removeAllRanges();
     // If the workspace is editable, only allow scrolling when gripping empty
     // space.  Otherwise, allow scrolling when gripping anywhere.
     this.isScrolling = true;

demos/blockfactory/factory.js

@@ -699,7 +699,6 @@ function updatePreview() {
  * @param {string} id ID of <pre> element to inject into.
  */
 function injectCode(code, id) {
-  Blockly.removeAllRanges();
   var pre = document.getElementById(id);
   pre.textContent = code;
   code = pre.innerHTML;