diff --git a/autotests/decorationbuttontest.cpp b/autotests/decorationbuttontest.cpp
--- a/autotests/decorationbuttontest.cpp
+++ b/autotests/decorationbuttontest.cpp
@@ -1347,32 +1347,79 @@
 void DecorationButtonTest::testContains_data()
 {
     QTest::addColumn<QPointF>("pos");
-    QTest::addColumn<bool>("contains");
-
-    // Button geometry: QRectF(0, 0, 10, 10).
-    QTest::newRow("on left edge")   << QPointF(0, 5)  << true;
-    QTest::newRow("on top edge")    << QPointF(5, 0)  << true;
-    QTest::newRow("on right edge")  << QPointF(9, 5)  << true;
-    QTest::newRow("on bottom edge") << QPointF(5, 9)  << true;
-    QTest::newRow("inside")         << QPointF(5, 5)  << true;
-    QTest::newRow("outside 1")      << QPointF(-1, 5) << false;
-    QTest::newRow("outside 2")      << QPointF(5, -1) << false;
-    QTest::newRow("outside 3")      << QPointF(10, 5) << false;
-    QTest::newRow("outside 4")      << QPointF(5, 10) << false;
+    QTest::addColumn<bool>("containsInt");
+    QTest::addColumn<bool>("containsFloat");
+    QTest::addColumn<bool>("containsNegative");
+
+
+    /*
+     *
+     * Rect ***: QRectF(0, 0, 10, 10)
+     * Rect ooo: QRectF(0.1, 0.1, 10.1, 10.1)
+     * Rect ###: QRectF(10.1, 10, -10, -9.9)
+     *
+     *
+     * (0,0)       (0,0.1)          (10,0)  (10.1,0)          x
+     *          ------------BBB------------------------------>
+     *          |                      *
+     *          |                      *
+     * (0,0.1)  |     o#o#o#DDD#o#o#o#o#o#o#o#o
+     *          |     #                *      #
+     *         AAA   CCC  INSIDE      EEE    GGG
+     *          |     #                *      #
+     *          |     o                *      o
+     *          |     #                *      #
+     *          |     o                *      o
+     * (0,10)   |* * *#*#*#*FFF*#*#*#*#*# # # #
+     *          |     o                       o
+     *          |     o                       o
+     * (0,10.1) |     o o o HHH o o o o o o o o
+     *          |
+     *          |
+     *          v
+     *         y
+     *
+     */
+
+    QTest::newRow("INSIDE") << QPointF(5, 5)  << true << true << true;
+
+    QTest::newRow("left edge (AAA)")  << QPointF(0, 5)  << true << false << false;
+    QTest::newRow("top edge (BBB)")   << QPointF(5, 0)  << true << false << false;
+
+    QTest::newRow("near left edge (CCC)") << QPointF(0.1, 5)  << true << true << true;
+    QTest::newRow("near top edge (DDD)")  << QPointF(5, 0.1)  << true << true << true;
+
+    QTest::newRow("near right edge (EEE)")    << QPointF(10, 5)  << false << true << true;
+    QTest::newRow("near bottom edge (FFF)")   << QPointF(5, 10)  << false << true << false;
+
+    QTest::newRow("right edge (GGG)")    << QPointF(10.1, 5)  << false << false << false;
+    QTest::newRow("bottom edge (HHH)")   << QPointF(5, 10.1)  << false << false << false;
+
+    QTest::newRow("outside 1")    << QPointF(-1, 5) << false << false << false;
+    QTest::newRow("outside 2")    << QPointF(5, -1) << false << false << false;
+    QTest::newRow("outside 3")    << QPointF(10.101, 5) << false << false << false;
+    QTest::newRow("outside 4")    << QPointF(5, 10.101) << false << false << false;
 }
 
 void DecorationButtonTest::testContains()
 {
     MockBridge bridge;
     MockDecoration mockDecoration(&bridge);
 
+    QFETCH(QPointF, pos);
+
     MockButton button(KDecoration2::DecorationButtonType::Custom, &mockDecoration);
-    button.setGeometry(QRectF(0, 0, 10, 10));
     button.setEnabled(true);
     button.setVisible(true);
 
-    QFETCH(QPointF, pos);
-    QTEST(button.contains(pos), "contains");
+    button.setGeometry(QRectF(0, 0, 10, 10));
+    QTEST(button.contains(pos), "containsInt");
+
+    button.setGeometry(QRectF(0.1, 0.1, 10, 10));
+    QTEST(button.contains(pos), "containsFloat");
+
+    button.setGeometry(QRectF(10.1, 10, -10, -9.9));
+    QTEST(button.contains(pos), "containsNegative");
 }
 
 QTEST_MAIN(DecorationButtonTest)
diff --git a/src/decorationbutton.cpp b/src/decorationbutton.cpp
--- a/src/decorationbutton.cpp
+++ b/src/decorationbutton.cpp
@@ -447,7 +447,16 @@
 
 bool DecorationButton::contains(const QPointF &pos) const
 {
-    return d->geometry.toRect().contains(pos.toPoint());
+    if (!d->geometry.contains(pos)) {
+        return false;
+    }
+
+    // additional make sure pos is not on the right or bottom edge
+    const bool horizontalInside = d->geometry.width() < 0 ? pos.x() < d->geometry.x() :
+                                                            pos.x() < d->geometry.right();
+    const bool verticalInside = d->geometry.height() < 0 ? pos.y() < d->geometry.y() :
+                                                           pos.y() < d->geometry.bottom();
+    return horizontalInside && verticalInside;
 }
 
 bool DecorationButton::event(QEvent *event)