Apply offset to column index depending on presense of selection column (#11667)

* Apply offset to column index depending on presense of selection column

After testing this manually I noticed that offset correction needs to be negative

* Add the testing UI

1 files changed, 5 insertions, 1 deletions

diff --git a/client/src/main/java/com/vaadin/client/widgets/Grid.java b/client/src/main/java/com/vaadin/client/widgets/Grid.java
index 9f82d3339f..76fe46fbb7 100755
--- a/client/src/main/java/com/vaadin/client/widgets/Grid.java
+++ b/client/src/main/java/com/vaadin/client/widgets/Grid.java
@@ -7958,7 +7958,11 @@ public class Grid<T> extends ResizeComposite implements HasSelectionHandlers<T>,
             if (!event.getCell().isHeader()) {
                 return;
             }
-            if (event.getCell().getColumnIndex() < getFrozenColumnCount()) {
+            int offset = 0; // apply offset depending on selection column, see #10546
+            if (getSelectionColumn().isPresent()) {
+                offset = -1;
+            }
+            if (event.getCell().getColumnIndex()+offset < getFrozenColumnCount()) {
                 return;
             }