Double click message will not into the
1. -> onExited : handleHovered = false
2. -> onPressed will into if (handleHovered) {...} even we release the handle
hovered.
3. -> Then will cause not updateHandlePosition( ) so, this process will not
post this message to Slider :: onSliderValueChanged() {..}
4. -> So click will not change the UI

[Fix Solution]
6. After change the target add below code (line "b"), it can get
positive result

File %QT path%:\Qt\Tools\QtCreator\bin\qml\QtQuick\Controls\Slider.qml

onReleased: {
updateHandlePosition(mouse, Settings.hasTouchScreen)
// If we don't update while dragging, this is the only
// moment that the range is updated.
if (!slider.updateValueWhileDragging)
range.position = __horizontal ? fakeHandle.x : fakeHandle.y;
clickOffset = 0
preventStealing = false
a. // should release the hovered in all case.
b. handleHovered = false
}