Why is there a dead zone on the right side of my flipable?

igor_stravinsky

I'm working on a simple Qt Quick Controls 2 app

In it, I have a view which uses a ScrollView with a ScrollBar in it. When that's the only screen, the vertical scroll bar responds to gestures or when the I click on the scroll bar thumb and drag.

If I put that same view inside of a Flipable, and make it the flipable's front view, the scroll bar on the right side of the view becomes unresponsive to being clicked. It still responds to gestures, however.

Through trial and error, I discovered that if I move the scroll bar in 10 pixels from the right side of the window, the scroll bar behaves normally. The problem isn't limited to scroll bars, however. If I put a 10 pixel wide button on the right side of the screen in a Flipable, it can't be clicked on.

What is happening here? Did I miss a bit of documentation that says that controls on the edges of Flipables aren't clickable? Is there some invisible border in a flipable that I can't see?

My main window is pretty much copied and pasted from the qml example code. My front side view looks like this:

Item {
    id:frontSide
    anchors.fill:parent

    ScrollView{
        id:frontScrollView
        anchors.fill:parent
        contentHeight: a_text.height
        contentWidth: a_text.width

        ScrollBar.vertical: ScrollBar{
            anchors.top: parent.top
            anchors.bottom:parent.bottom
            anchors.right:parent.right
            anchors.rightMargin: 10 //remove this, and the scroll bar won't be clickable
            policy: ScrollBar.AlwaysOn

        }

        Text{
            id:a_text
            text:"a"
            font.family: "helvetica"
            font.pointSize: 1000
        }
}
}

Leon_2001

I am not an expert, but as you use ScrollView from Qt Quick Controls 2.x, Scrollbars are already attached to it. So you don't have to do this again.
Nevertheless, you can still change properties of it. So if you wish to have it always on, just use ScrollBar.vertical.policy: ScrollBar.AlywaysOn

import QtQuick.Controls 2.3
import QtQuick 2.10

ApplicationWindow {
  width: 500; height: 500
  visible: true

  Item {
    id:frontSide
    anchors.fill:parent

    ScrollView{
      id:frontScrollView
      anchors.fill:parent
      contentHeight: a_text.height
      contentWidth: a_text.width

      ScrollBar.vertical.policy: ScrollBar.AlwaysOn

      Text{
          id:a_text
          text:"a"
          font.family: "helvetica"
          font.pointSize: 1000
      }
    }
  }
}

igor_stravinsky

@Leon_2001 You're absolutely right about the ScrollBars inside of a ScrollView.

I bracket them when I'm changing a lot of parameters, so I don't have to type ScrollBar.vertical.* over and over. If I were just changing the policy, I'd do it as you did.

Leon_2001

I am not quite sure if you see your mistake? If you want to change a lot of parameters you still have to do it like this.

ScrollBar.vertical {
  ...
}

instead of

ScrollBar.vertical: ScrollBar {
}

Because in the second version you would attach a (new) scrollbar to a Flickable. But you haven't used a Flickable and ScrollView already provides two Scrollbars -> this also means, you don't have to position them.

igor_stravinsky

@Leon_2001 Thanks for pointing that out!

I was doing that in a simple example, my real project has scrollbars inside a ListView, where you do need to do

ScrollBar.vertical: ScrollBar {
}

It's interesting that creating a new scroll bar in a ScrollView created the same issue. That must have put two scroll bars on top of each other, and the visible one wouldn't respond to clicks.

igor_stravinsky

It turned out that this was caused because the back side of the flippable has a drawer on it.

The Drawer has a drag margin on the right side, and this margin corresponds to the dead zone on the right of all other views. In the case of the scroll bar, having it on the right side made it impossible to use the scroll thumbs to scroll the view.

This has been logged as QTBUG-68748
https://bugreports.qt.io/browse/QTBUG-68748