First commit.

Signed-off-by: Chen Xiao <abigwc@gmail.com>

client/node_modules/d3-drag/src/nodrag.js

@@ -0,0 +1,28 @@
+import {select} from "d3-selection";
+import noevent, {nonpassivecapture} from "./noevent.js";
+
+export default function(view) {
+  var root = view.document.documentElement,
+      selection = select(view).on("dragstart.drag", noevent, nonpassivecapture);
+  if ("onselectstart" in root) {
+    selection.on("selectstart.drag", noevent, nonpassivecapture);
+  } else {
+    root.__noselect = root.style.MozUserSelect;
+    root.style.MozUserSelect = "none";
+  }
+}
+
+export function yesdrag(view, noclick) {
+  var root = view.document.documentElement,
+      selection = select(view).on("dragstart.drag", null);
+  if (noclick) {
+    selection.on("click.drag", noevent, nonpassivecapture);
+    setTimeout(function() { selection.on("click.drag", null); }, 0);
+  }
+  if ("onselectstart" in root) {
+    selection.on("selectstart.drag", null);
+  } else {
+    root.style.MozUserSelect = root.__noselect;
+    delete root.__noselect;
+  }
+}