Issues with framelesswindow dragging

[adutzu89]

I'm trying to implement a custom decorator bar for my application but I ran into a couple of issues.

I'm developing & testing on Ubuntu 16.04.1, AMD64 using Qt Creator 4.0.3 with Qt 5.7.0.

First issue: the window is shaking when position is changed
Second issue: the windows does not touch the top panel unless maximized

Here is the code to the MouseArea :

MouseArea {
                    Layout.fillWidth: false
                    Layout.fillHeight: true
                    Layout.preferredWidth: decoratorBar.width - windowControl.width
                    cursorShape: Qt.PointingHandCursor
                    acceptedButtons: Qt.LeftButton
                    property point clickPos
                    onPressed: {
                        clickPos = Qt.point(mouse.x,mouse.y)
                    }
                    onPositionChanged: {
                        var delta = Qt.point(mouse.x - clickPos.x, mouse.y - clickPos.y)
                        applicationWindow.x = applicationWindow.x + delta.x
                        applicationWindow.y = applicationWindow.y + delta.y
                    }
                }

Any ideeas?
Thank you.