diff --git a/abstract_client.h b/abstract_client.h
--- a/abstract_client.h
+++ b/abstract_client.h
@@ -578,6 +578,8 @@
     */
     virtual void showContextHelp();
 
+    QRect inputGeometry() const override;
+
     // TODO: remove boolean trap
     static bool belongToSameApplication(const AbstractClient* c1, const AbstractClient* c2, bool active_hack = false);
 
diff --git a/abstract_client.cpp b/abstract_client.cpp
--- a/abstract_client.cpp
+++ b/abstract_client.cpp
@@ -1627,4 +1627,12 @@
     return candidateGeom.translated(candidatePanel->pos());
 }
 
+QRect AbstractClient::inputGeometry() const
+{
+    if (isDecorated()) {
+        return Toplevel::inputGeometry() + decoration()->resizeOnlyBorders();
+    }
+    return Toplevel::inputGeometry();
+}
+
 }
diff --git a/autotests/integration/decoration_input_test.cpp b/autotests/integration/decoration_input_test.cpp
--- a/autotests/integration/decoration_input_test.cpp
+++ b/autotests/integration/decoration_input_test.cpp
@@ -70,6 +70,8 @@
     void testPressToMove();
     void testTapToMove_data();
     void testTapToMove();
+    void testResizeOutsideWindow_data();
+    void testResizeOutsideWindow();
 
 private:
     AbstractClient *showWindow(Test::ShellSurfaceType type);
@@ -498,6 +500,69 @@
     QCOMPARE(c->pos(), oldPos + offset2 + offset3);
 }
 
+void DecorationInputTest::testResizeOutsideWindow_data()
+{
+    QTest::addColumn<Test::ShellSurfaceType>("type");
+    QTest::addColumn<Qt::Edge>("edge");
+    QTest::addColumn<Qt::CursorShape>("expectedCursor");
+
+    QTest::newRow("wlShell - left") << Test::ShellSurfaceType::WlShell << Qt::LeftEdge << Qt::SizeHorCursor;
+    QTest::newRow("xdgShellV5 - left") << Test::ShellSurfaceType::XdgShellV5 << Qt::LeftEdge << Qt::SizeHorCursor;
+    QTest::newRow("wlShell - right") << Test::ShellSurfaceType::WlShell << Qt::RightEdge << Qt::SizeHorCursor;
+    QTest::newRow("xdgShellV5 - right") << Test::ShellSurfaceType::XdgShellV5 << Qt::RightEdge << Qt::SizeHorCursor;
+    QTest::newRow("wlShell - bottom") << Test::ShellSurfaceType::WlShell << Qt::BottomEdge << Qt::SizeVerCursor;
+    QTest::newRow("xdgShellV5 - bottom") << Test::ShellSurfaceType::XdgShellV5 << Qt::BottomEdge << Qt::SizeVerCursor;
+}
+
+void DecorationInputTest::testResizeOutsideWindow()
+{
+    // this test verifies that one can resize the window outside the decoration with NoSideBorder
+
+    // first adjust config
+    kwinApp()->config()->group("org.kde.kdecoration2").writeEntry("BorderSize", QStringLiteral("None"));
+    kwinApp()->config()->sync();
+    workspace()->slotReconfigure();
+
+    // now create window
+    QFETCH(Test::ShellSurfaceType, type);
+    AbstractClient *c = showWindow(type);
+    QVERIFY(c);
+    QVERIFY(c->isDecorated());
+    QVERIFY(!c->noBorder());
+    c->move(screens()->geometry(0).center() - QPoint(c->width()/2, c->height()/2));
+    QVERIFY(c->geometry() != c->inputGeometry());
+    QVERIFY(c->inputGeometry().contains(c->geometry()));
+    QSignalSpy startMoveResizedSpy(c, &AbstractClient::clientStartUserMovedResized);
+    QVERIFY(startMoveResizedSpy.isValid());
+
+    // go to border
+    quint32 timestamp = 1;
+    QFETCH(Qt::Edge, edge);
+    switch (edge) {
+    case Qt::LeftEdge:
+        MOTION(QPoint(c->geometry().x() -1, c->geometry().center().y()));
+        break;
+    case Qt::RightEdge:
+        MOTION(QPoint(c->geometry().x() + c->geometry().width() +1, c->geometry().center().y()));
+        break;
+    case Qt::BottomEdge:
+        MOTION(QPoint(c->geometry().center().x(), c->geometry().y() + c->geometry().height() + 1));
+        break;
+    default:
+        break;
+    }
+    QVERIFY(!c->geometry().contains(KWin::Cursor::pos()));
+
+    // pressing should trigger resize
+    PRESS;
+    QVERIFY(!c->isResize());
+    QVERIFY(startMoveResizedSpy.wait());
+    QVERIFY(c->isResize());
+
+    RELEASE;
+    QVERIFY(!c->isResize());
+}
+
 }
 
 WAYLANDTEST_MAIN(KWin::DecorationInputTest)
diff --git a/input.cpp b/input.cpp
--- a/input.cpp
+++ b/input.cpp
@@ -1451,7 +1451,7 @@
                 continue;
             }
         }
-        if (t->geometry().contains(pos) && acceptsInput(t, pos)) {
+        if (t->inputGeometry().contains(pos) && acceptsInput(t, pos)) {
             return t;
         }
     } while (it != stacking.begin());
diff --git a/toplevel.h b/toplevel.h
--- a/toplevel.h
+++ b/toplevel.h
@@ -219,6 +219,13 @@
      **/
     virtual quint32 windowId() const;
     QRect geometry() const;
+    /**
+     * The geometry of the Toplevel which accepts input events. This might be larger
+     * than the actual geometry, e.g. to support resizing outside the window.
+     *
+     * Default implementation returns same as geometry.
+     **/
+    virtual QRect inputGeometry() const;
     QSize size() const;
     QPoint pos() const;
     QRect rect() const;
diff --git a/toplevel.cpp b/toplevel.cpp
--- a/toplevel.cpp
+++ b/toplevel.cpp
@@ -538,5 +538,10 @@
     return window();
 }
 
+QRect Toplevel::inputGeometry() const
+{
+    return geometry();
+}
+
 } // namespace