[Spreadsheet] Replace override cursor with QGraphicsItem::setCursor (#22097)

* [Spreadsheet] Replace the risky use of override cursor with
QGraphicsItem::setCursor

* [pre-commit.ci] auto fixes from pre-commit.com hooks

for more information, see https://pre-commit.ci

---------

Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>

src/Mod/Spreadsheet/Gui/SheetTableView.cpp

@@ -60,19 +60,18 @@ using namespace App;
 void SheetViewHeader::mouseMoveEvent(QMouseEvent* e)
 {
     // for some reason QWidget::setCursor() has no effect in QGraphicsView
-    // therefore we resort to override cursor
+    // therefore we resort to QGraphicsItem::setCursor
     const QCursor currentCursor = this->cursor();
     QHeaderView::mouseMoveEvent(e);
     const QCursor newerCursor = this->cursor();
     if (newerCursor != currentCursor) {
-        qApp->setOverrideCursor(newerCursor);
+        Q_EMIT cursorChanged(newerCursor);
     }
 }
 
 void SheetViewHeader::mouseReleaseEvent(QMouseEvent* event)
 {
     QHeaderView::mouseReleaseEvent(event);
-    qApp->setOverrideCursor(Qt::ArrowCursor);
     Q_EMIT resizeFinished();
 }
 

src/Mod/Spreadsheet/Gui/SheetTableView.h

@@ -45,6 +45,7 @@ public:
     }
 Q_SIGNALS:
     void resizeFinished();
+    void cursorChanged(QCursor);
 
 protected:
     void mouseMoveEvent(QMouseEvent* e) override;

src/Mod/Spreadsheet/Gui/ZoomableView.cpp

@@ -122,6 +122,18 @@ ZoomableView::ZoomableView(Ui::Sheet* ui)
     });
 
     resetZoom();
+
+    auto connectCursorChangedSignal = [this](QHeaderView* hv) {
+        auto header = qobject_cast<SpreadsheetGui::SheetViewHeader*>(hv);
+        connect(header,
+                &SpreadsheetGui::SheetViewHeader::cursorChanged,
+                this,
+                [this](const QCursor& newerCursor) {
+                    qpw->setCursor(newerCursor);
+                });
+    };
+    connectCursorChangedSignal(stv->horizontalHeader());
+    connectCursorChangedSignal(stv->verticalHeader());
 }
 
 int ZoomableView::zoomLevel() const