Bug 1357206 part 4. Don't move the cursor even if eSetValue_MoveCursorToEndIfValueChanged is set, if the value did not change. r=ehsan

devtools/client/debugger/new/test/mochitest/browser_dbg-breakpoints-cond.js

@@ -13,6 +13,8 @@ function setConditionalBreakpoint(dbg, index, condition) {
     selectMenuItem(dbg, 2);
     yield waitForElement(dbg, ".conditional-breakpoint-panel input");
     findElementWithSelector(dbg, ".conditional-breakpoint-panel input").focus();
+    // Position cursor reliably at the end of the text.
+    pressKey(dbg, "End")
     type(dbg, condition);
     pressKey(dbg, "Enter");
   });

devtools/client/debugger/new/test/mochitest/browser_dbg-expressions.js

@@ -32,6 +32,8 @@ async function addExpression(dbg, input) {
 async function editExpression(dbg, input) {
   info("updating the expression");
   dblClickElement(dbg, "expressionNode", 1);
+  // Position cursor reliably at the end of the text.
+  pressKey(dbg, "End")
   type(dbg, input);
   pressKey(dbg, "Enter");
   await waitForDispatch(dbg, "EVALUATE_EXPRESSION");

devtools/client/debugger/new/test/mochitest/head.js

@@ -560,6 +560,10 @@ const keyMappings = {
   Enter: { code: "VK_RETURN" },
   Up: { code: "VK_UP" },
   Down: { code: "VK_DOWN" },
+  Right: { code: "VK_RIGHT" },
+  Left: { code: "VK_LEFT" },
+  End: { code: "VK_RIGHT", modifiers: cmdOrCtrl },
+  Start: { code: "VK_LEFT", modifiers: cmdOrCtrl },
   Tab: { code: "VK_TAB" },
   Escape: { code: "VK_ESCAPE" },
   pauseKey: { code: "VK_F8" },

dom/base/nsContentUtils.cpp

@@ -297,6 +297,7 @@ bool nsContentUtils::sUseActivityCursor = false;
 bool nsContentUtils::sAnimationsAPICoreEnabled = false;
 bool nsContentUtils::sAnimationsAPIElementAnimateEnabled = false;
 bool nsContentUtils::sGetBoxQuadsEnabled = false;
+bool nsContentUtils::sSkipCursorMoveForSameValueSet = false;
 
 int32_t nsContentUtils::sPrivacyMaxInnerWidth = 1000;
 int32_t nsContentUtils::sPrivacyMaxInnerHeight = 1000;
@@ -645,6 +646,10 @@ nsContentUtils::Init()
   Preferences::AddBoolVarCache(&sGetBoxQuadsEnabled,
                                "layout.css.getBoxQuads.enabled", false);
 
+  Preferences::AddBoolVarCache(&sSkipCursorMoveForSameValueSet,
+                               "dom.input.skip_cursor_move_for_same_value_set",
+                               true);
+
   Element::InitCCCallbacks();
 
   nsCOMPtr<nsIUUIDGenerator> uuidGenerator =

dom/base/nsContentUtils.h

@@ -2888,6 +2888,13 @@ public:
    */
   static uint64_t GenerateTabId();
 
+  /**
+   * Check whether we should skip moving the cursor for a same-value .value set
+   * on a text input or textarea.
+   */
+  static bool
+  SkipCursorMoveForSameValueSet() { return sSkipCursorMoveForSameValueSet; }
+
 private:
   static bool InitializeEventTable();
 
@@ -3012,6 +3019,7 @@ private:
   static bool sAnimationsAPICoreEnabled;
   static bool sAnimationsAPIElementAnimateEnabled;
   static bool sGetBoxQuadsEnabled;
+  static bool sSkipCursorMoveForSameValueSet;
   static uint32_t sCookiesLifetimePolicy;
   static uint32_t sCookiesBehavior;
 

dom/html/nsTextEditorState.cpp

@@ -2636,26 +2636,41 @@ nsTextEditorState::SetValue(const nsAString& aValue, uint32_t aFlags)
     if (!mValue) {
       mValue.emplace();
     }
-    if (!mValue->Assign(newValue, fallible)) {
-      return false;
-    }
 
-    // Since we have no editor we presumably have cached selection state.
-    if (IsSelectionCached()) {
-      SelectionProperties& props = GetSelectionProperties();
-      if (aFlags & eSetValue_MoveCursorToEndIfValueChanged) {
-        props.SetStart(newValue.Length());
-        props.SetEnd(newValue.Length());
-      } else {
-        // Make sure our cached selection position is not outside the new value.
-        props.SetStart(std::min(props.GetStart(), newValue.Length()));
-        props.SetEnd(std::min(props.GetEnd(), newValue.Length()));
+    // We can't just early-return here if mValue->Equals(newValue), because
+    // ValueWasChanged and OnValueChanged below still need to be called.
+    if (!mValue->Equals(newValue) ||
+        !nsContentUtils::SkipCursorMoveForSameValueSet()) {
+      if (!mValue->Assign(newValue, fallible)) {
+        return false;
       }
-    }
 
-    // Update the frame display if needed
-    if (mBoundFrame) {
-      mBoundFrame->UpdateValueDisplay(true);
+      // Since we have no editor we presumably have cached selection state.
+      if (IsSelectionCached()) {
+        SelectionProperties& props = GetSelectionProperties();
+        if (aFlags & eSetValue_MoveCursorToEndIfValueChanged) {
+          props.SetStart(newValue.Length());
+          props.SetEnd(newValue.Length());
+        } else {
+          // Make sure our cached selection position is not outside the new value.
+          props.SetStart(std::min(props.GetStart(), newValue.Length()));
+          props.SetEnd(std::min(props.GetEnd(), newValue.Length()));
+        }
+      }
+
+      // Update the frame display if needed
+      if (mBoundFrame) {
+        mBoundFrame->UpdateValueDisplay(true);
+      }
+    } else {
+      // Even if our value is not actually changing, apparently we need to mark
+      // our SelectionProperties dirty to make accessibility tests happy.
+      // Probably because they depend on the SetSelectionRange() call we make on
+      // our frame in RestoreSelectionState, but I have no idea why they do.
+      if (IsSelectionCached()) {
+        SelectionProperties& props = GetSelectionProperties();
+        props.SetIsDirty();
+      }
     }
   }
 

dom/html/nsTextEditorState.h

@@ -282,11 +282,16 @@ public:
         mIsDirty = true;
         mDirection = value;
       }
-      // return true only if mStart, mEnd, or mDirection have been modified
+      // return true only if mStart, mEnd, or mDirection have been modified,
+      // or if SetIsDirty() was explicitly called.
       bool IsDirty() const
       {
         return mIsDirty;
       }
+      void SetIsDirty()
+      {
+        mIsDirty = true;
+      }
     private:
       uint32_t mStart, mEnd;
       bool mIsDirty = false;

modules/libpref/init/all.js

@@ -1251,6 +1251,10 @@ pref("dom.select_popup_in_parent.enabled", false);
 // Enable Directory API. By default, disabled.
 pref("dom.input.dirpicker", false);
 
+// Enable not moving the cursor to end when a text input or textarea has .value
+// set to the value it already has.  By default, enabled.
+pref("dom.input.skip_cursor_move_for_same_value_set", true);
+
 // Enables system messages and activities
 pref("dom.sysmsg.enabled", false);