diff --git a/src/com/android/launcher3/AppWidgetResizeFrame.java b/src/com/android/launcher3/AppWidgetResizeFrame.java
index ee71146..fef3f8f 100644
--- a/src/com/android/launcher3/AppWidgetResizeFrame.java
+++ b/src/com/android/launcher3/AppWidgetResizeFrame.java
@@ -2,6 +2,7 @@
 
 import static android.appwidget.AppWidgetHostView.getDefaultPaddingForWidget;
 
+import static com.android.launcher3.CellLayout.SPRING_LOADED_PROGRESS;
 import static com.android.launcher3.LauncherAnimUtils.LAYOUT_HEIGHT;
 import static com.android.launcher3.LauncherAnimUtils.LAYOUT_WIDTH;
 import static com.android.launcher3.logging.StatsLogManager.LauncherEvent.LAUNCHER_WIDGET_RESIZE_COMPLETED;
@@ -9,6 +10,8 @@
 import static com.android.launcher3.views.BaseDragLayer.LAYOUT_X;
 import static com.android.launcher3.views.BaseDragLayer.LAYOUT_Y;
 
+import android.animation.Animator;
+import android.animation.AnimatorListenerAdapter;
 import android.animation.AnimatorSet;
 import android.animation.ObjectAnimator;
 import android.animation.PropertyValuesHolder;
@@ -29,6 +32,7 @@
 
 import com.android.launcher3.accessibility.DragViewStateAnnouncer;
 import com.android.launcher3.dragndrop.DragLayer;
+import com.android.launcher3.keyboard.ViewGroupFocusHelper;
 import com.android.launcher3.logging.InstanceId;
 import com.android.launcher3.logging.InstanceIdSequence;
 import com.android.launcher3.model.data.ItemInfo;
@@ -49,12 +53,14 @@
     private static final String KEY_RECONFIGURABLE_WIDGET_EDUCATION_TIP_SEEN =
             "launcher.reconfigurable_widget_education_tip_seen";
     private static final Rect sTmpRect = new Rect();
+    private static final Rect sTmpRect2 = new Rect();
 
     private static final int HANDLE_COUNT = 4;
     private static final int INDEX_LEFT = 0;
     private static final int INDEX_TOP = 1;
     private static final int INDEX_RIGHT = 2;
     private static final int INDEX_BOTTOM = 3;
+    private static final float MIN_OPACITY_FOR_CELL_LAYOUT_DURING_INVALID_RESIZE = 0.5f;
 
     private final Launcher mLauncher;
     private final DragViewStateAnnouncer mStateAnnouncer;
@@ -103,6 +109,16 @@
 
     private final InstanceId logInstanceId = new InstanceIdSequence().newInstanceId();
 
+    private final ViewGroupFocusHelper mDragLayerRelativeCoordinateHelper;
+
+    /**
+     * In the two panel UI, it is not possible to resize a widget to cross its host
+     * {@link CellLayout}'s sibling. When this happens, we gradually reduce the opacity of the
+     * sibling {@link CellLayout} from 1f to
+     * {@link #MIN_OPACITY_FOR_CELL_LAYOUT_DURING_INVALID_RESIZE}.
+     */
+    private final float mDragAcrossTwoPanelOpacityMargin;
+
     private boolean mLeftBorderActive;
     private boolean mRightBorderActive;
     private boolean mTopBorderActive;
@@ -149,6 +165,10 @@
         for (int i = 0; i < HANDLE_COUNT; i++) {
             mSystemGestureExclusionRects.add(new Rect());
         }
+
+        mDragAcrossTwoPanelOpacityMargin = mLauncher.getResources().getDimensionPixelSize(
+                R.dimen.resize_frame_invalid_drag_across_two_panel_opacity_margin);
+        mDragLayerRelativeCoordinateHelper = new ViewGroupFocusHelper(mLauncher.getDragLayer());
     }
 
     @Override
@@ -359,6 +379,37 @@
             lp.y = sTmpRect.top;
         }
 
+        // Handle invalid resize across CellLayouts in the two panel UI.
+        if (mCellLayout.getParent() instanceof Workspace) {
+            Workspace workspace = (Workspace) mCellLayout.getParent();
+            CellLayout pairedCellLayout = workspace.getScreenPair(mCellLayout);
+            if (pairedCellLayout != null) {
+                Rect focusedCellLayoutBound = sTmpRect;
+                mDragLayerRelativeCoordinateHelper.viewToRect(mCellLayout, focusedCellLayoutBound);
+                Rect resizeFrameBound = sTmpRect2;
+                findViewById(R.id.widget_resize_frame).getGlobalVisibleRect(resizeFrameBound);
+                float progress = 1f;
+                if (workspace.indexOfChild(pairedCellLayout) < workspace.indexOfChild(mCellLayout)
+                        && mDeltaX < 0
+                        && resizeFrameBound.left < focusedCellLayoutBound.left) {
+                    // Resize from right to left.
+                    progress = (mDragAcrossTwoPanelOpacityMargin + mDeltaX)
+                            / mDragAcrossTwoPanelOpacityMargin;
+                } else if (workspace.indexOfChild(pairedCellLayout)
+                                > workspace.indexOfChild(mCellLayout)
+                        && mDeltaX > 0
+                        && resizeFrameBound.right > focusedCellLayoutBound.right) {
+                    // Resize from left to right.
+                    progress = (mDragAcrossTwoPanelOpacityMargin - mDeltaX)
+                            / mDragAcrossTwoPanelOpacityMargin;
+                }
+                float alpha = Math.max(MIN_OPACITY_FOR_CELL_LAYOUT_DURING_INVALID_RESIZE, progress);
+                float springLoadedProgress = Math.min(1f, 1f - progress);
+                updateInvalidResizeEffect(mCellLayout, pairedCellLayout, alpha,
+                        springLoadedProgress);
+            }
+        }
+
         requestLayout();
     }
 
@@ -515,13 +566,24 @@
         }
 
         final DragLayer.LayoutParams lp = (DragLayer.LayoutParams) getLayoutParams();
+        final CellLayout pairedCellLayout;
+        if (mCellLayout.getParent() instanceof Workspace) {
+            Workspace workspace = (Workspace) mCellLayout.getParent();
+            pairedCellLayout = workspace.getScreenPair(mCellLayout);
+        } else {
+            pairedCellLayout = null;
+        }
         if (!animate) {
             lp.width = newWidth;
             lp.height = newHeight;
             lp.x = newX;
             lp.y = newY;
             for (int i = 0; i < HANDLE_COUNT; i++) {
-                mDragHandles[i].setAlpha(1.0f);
+                mDragHandles[i].setAlpha(1f);
+            }
+            if (pairedCellLayout != null) {
+                updateInvalidResizeEffect(mCellLayout, pairedCellLayout, /* alpha= */ 1f,
+                        /* springLoadedProgress= */ 0f);
             }
             requestLayout();
         } else {
@@ -538,6 +600,10 @@
                 set.play(mFirstFrameAnimatorHelper.addTo(
                         ObjectAnimator.ofFloat(mDragHandles[i], ALPHA, 1f)));
             }
+            if (pairedCellLayout != null) {
+                updateInvalidResizeEffect(mCellLayout, pairedCellLayout, /* alpha= */ 1f,
+                        /* springLoadedProgress= */ 0f, /* animatorSet= */ set);
+            }
             set.setDuration(SNAP_DURATION);
             set.start();
         }
@@ -624,6 +690,52 @@
         }
     }
 
+    private void updateInvalidResizeEffect(CellLayout cellLayout, CellLayout pairedCellLayout,
+            float alpha, float springLoadedProgress) {
+        updateInvalidResizeEffect(cellLayout, pairedCellLayout, alpha,
+                springLoadedProgress, /* animatorSet= */ null);
+    }
+
+    private void updateInvalidResizeEffect(CellLayout cellLayout, CellLayout pairedCellLayout,
+            float alpha, float springLoadedProgress, @Nullable AnimatorSet animatorSet) {
+        int childCount = pairedCellLayout.getChildCount();
+        for (int i = 0; i < childCount; i++) {
+            View child = pairedCellLayout.getChildAt(i);
+            if (animatorSet != null) {
+                animatorSet.play(
+                        mFirstFrameAnimatorHelper.addTo(
+                                ObjectAnimator.ofFloat(child, ALPHA, alpha)));
+            } else {
+                child.setAlpha(alpha);
+            }
+        }
+        if (animatorSet != null) {
+            animatorSet.play(mFirstFrameAnimatorHelper.addTo(
+                    ObjectAnimator.ofFloat(cellLayout, SPRING_LOADED_PROGRESS,
+                            springLoadedProgress)));
+            animatorSet.play(mFirstFrameAnimatorHelper.addTo(
+                    ObjectAnimator.ofFloat(pairedCellLayout, SPRING_LOADED_PROGRESS,
+                            springLoadedProgress)));
+        } else {
+            cellLayout.setSpringLoadedProgress(springLoadedProgress);
+            pairedCellLayout.setSpringLoadedProgress(springLoadedProgress);
+        }
+
+        boolean shouldShowCellLayoutBorder = springLoadedProgress > 0f;
+        if (animatorSet != null) {
+            animatorSet.addListener(new AnimatorListenerAdapter() {
+                @Override
+                public void onAnimationEnd(Animator animator) {
+                    cellLayout.setIsDragOverlapping(shouldShowCellLayoutBorder);
+                    pairedCellLayout.setIsDragOverlapping(shouldShowCellLayoutBorder);
+                }
+            });
+        } else {
+            cellLayout.setIsDragOverlapping(shouldShowCellLayoutBorder);
+            pairedCellLayout.setIsDragOverlapping(shouldShowCellLayoutBorder);
+        }
+    }
+
     @Override
     protected boolean isOfType(int type) {
         return (type & TYPE_WIDGET_RESIZE_FRAME) != 0;
diff --git a/src/com/android/launcher3/Launcher.java b/src/com/android/launcher3/Launcher.java
index ed9f044..31ff7d7 100644
--- a/src/com/android/launcher3/Launcher.java
+++ b/src/com/android/launcher3/Launcher.java
@@ -2114,7 +2114,7 @@
             actualIds.add(id);
         }
         int firstId = visibleIds.getArray().get(0);
-        int pairId = mWorkspace.getPagePair(firstId);
+        int pairId = mWorkspace.getScreenPair(firstId);
         // Double check that actual screenIds contains the visibleId, as empty screens are hidden
         // in single panel.
         if (actualIds.contains(firstId)) {
@@ -2198,7 +2198,7 @@
             // Some empty pages might have been removed while the phone was in a single panel
             // mode, so we want to add those empty pages back.
             IntSet screenIds = IntSet.wrap(orderedScreenIds);
-            orderedScreenIds.forEach(screenId -> screenIds.add(mWorkspace.getPagePair(screenId)));
+            orderedScreenIds.forEach(screenId -> screenIds.add(mWorkspace.getScreenPair(screenId)));
             orderedScreenIds = screenIds.getArray();
         }
 
diff --git a/src/com/android/launcher3/Workspace.java b/src/com/android/launcher3/Workspace.java
index 54b2c96..d748186 100644
--- a/src/com/android/launcher3/Workspace.java
+++ b/src/com/android/launcher3/Workspace.java
@@ -651,7 +651,7 @@
 
             // If the icon was dragged from Hotseat, there is no page pair
             if (isTwoPanelEnabled() && !(mDragSourceInternal.getParent() instanceof Hotseat)) {
-                int pagePairScreenId = getPagePair(dragObject.dragInfo.screenId);
+                int pagePairScreenId = getScreenPair(dragObject.dragInfo.screenId);
                 CellLayout pagePair = mWorkspaceScreens.get(pagePairScreenId);
                 if (pagePair == null) {
                     // TODO: after http://b/198820019 is fixed, remove this
@@ -917,16 +917,33 @@
     }
 
     /**
-     * Returns the page that is shown together with the given page when two panel is enabled.
+     * Returns the screen ID of a page that is shown together with the given page screen ID when the
+     * two panel UI is enabled.
      */
-    public int getPagePair(int page) {
-        if (page % 2 == 0) {
-            return page + 1;
+    public int getScreenPair(int screenId) {
+        if (screenId % 2 == 0) {
+            return screenId + 1;
         } else {
-            return page - 1;
+            return screenId - 1;
         }
     }
 
+    /**
+     * Returns {@link CellLayout} that is shown together with the given {@link CellLayout} when the
+     * two panel UI is enabled.
+     */
+    @Nullable
+    public CellLayout getScreenPair(CellLayout cellLayout) {
+        if (!isTwoPanelEnabled()) {
+            return null;
+        }
+        int screenId = getIdForScreen(cellLayout);
+        if (screenId == -1) {
+            return null;
+        }
+        return getScreenWithId(getScreenPair(screenId));
+    }
+
     public void stripEmptyScreens() {
         if (mLauncher.isWorkspaceLoading()) {
             // Don't strip empty screens if the workspace is still loading.
@@ -959,7 +976,7 @@
             Iterator<Integer> removeScreensIterator = removeScreens.iterator();
             while (removeScreensIterator.hasNext()) {
                 int pageToRemove = removeScreensIterator.next();
-                int pagePair = getPagePair(pageToRemove);
+                int pagePair = getScreenPair(pageToRemove);
                 if (!removeScreens.contains(pagePair)) {
                     // The page pair isn't empty so we want to remove the current page from the
                     // removable pages' collection