#4969 : Fix gutter click behaviour on touch devices

src/edit/CodeMirror.js

@@ -143,6 +143,8 @@ function registerEventHandlers(cm) {
     return dx * dx + dy * dy > 20 * 20
   }
   on(d.scroller, "touchstart", e => {
+    if (clickInGutter(cm, e)) return
+
     if (!signalDOMEvent(cm, e) && !isMouseLikeTouchEvent(e)) {
       d.input.ensurePolled()
       clearTimeout(touchFinished)

src/edit/mouse_events.js

@@ -326,8 +326,13 @@ function leftButtonSelect(cm, event, start, behavior) {
 // handlers for the corresponding event.
 function gutterEvent(cm, e, type, prevent) {
   let mX, mY
-  try { mX = e.clientX; mY = e.clientY }
-  catch(e) { return false }
+  if (e.type == "touchstart"){
+      try { mX = e.touches[0].clientX; mY = e.touches[0].clientY }
+      catch(e) { return false }
+  } else {
+      try { mX = e.clientX; mY = e.clientY }
+      catch(e) { return false }
+  }
   if (mX >= Math.floor(cm.display.gutters.getBoundingClientRect().right)) return false
   if (prevent) e_preventDefault(e)