ScrollBar scrolling when mouse move without left button pressing

[abcxyz-me]

• What version of the product are you using?
  -57.0.0

• What architecture x86 or x64?
  -x64

• On what operating system?
  -Win10

• Are you using WinForms, WPF or OffScreen?
  -WPF

• What steps will reproduce the problem?
  1)Run the official project 'CefSharp.Wpf.Example'
  2)Draging the scrollbar with left button pressing
  3)move the cursor out of the browser control(move to right side)with left button pressing
  4)release left button
  5)move in browser control,the scrollbar will scrolling with mouse moving

[martinburrows]

I'm also seeing this with the latest version 62 prerelease.

The scrolling behavior is also inconsistent with the behavior of other standard windows. When the mouse button is held down on the scrollbar and the mouse is moved out of the window slightly to the right, scrolling should continue (try it with your browser on this page) - CefSharp allows slight movement to the left when scrolling but not to the right. This makes it very difficult to use unless the window is maximized.

[martinburrows]

Hi @amaitland - the fix in 49463b2 still does not allow the mouse to be moved even slightly to the right of the scrolllbar when scrolling, this affects usablilty. Standard windows do allow the mouse to be moved either to the left or the right of the scrollbar.

I had better results by capturing the mouse instead - this works fine with the example app in Windows 10:

    protected override void OnMouseLeave(MouseEventArgs e)
    {
            if (!e.Handled && browser != null)
            {
                var modifiers = e.GetModifiers();
            
                if (modifiers == CefEventFlags.LeftMouseButton)
                {
                    Mouse.Capture(this, CaptureMode.SubTree);
                }
                else
                {
                    browser.GetHost().SendMouseMoveEvent(-1, -1, true, modifiers);
                }
                
                ((IWebBrowserInternal)this).SetTooltipText(null);
            }
    }

[amaitland]

@martinburrows Thanks for the feedback, as you can see that change has not been merged as limited testing has been done.

Comments on your code:

• Should be sending the correct coordinates for SendMouseMoveEvent, sending -1 gives weird results.
• For the Mouse.Capture you don't appear to be calling Mouse.Capture(null) to release the mouse, is there extra code? Or you haven't quite got that far yet?

We used Mouse.Capture in another piece of code, and it kept crashing, took ages to get the sequence just right, so I'd be reluctant to use it again, #1723 for reference. Though I will concede it is probably the only solution.

[martinburrows]

Thanks for the reply @amaitland, yes I wasn't sure of the best way for Mouse.Capture(null) to be called, if I get the time I'll look into it further.

[amaitland]

For now going with my original set of changes as I think it's at least an improvement.

Merged in dd4b7d6

By all means submit a PR that Captures the mouse (and releases the capture).

[amaitland]

Possibly Mouse.PreviewMouseUpOutsideCapturedElement attached event might be usable here.

https://msdn.microsoft.com/en-us/library/system.windows.input.mouse.previewmouseupoutsidecapturedelement(v=vs.110).aspx

[martinburrows]

Thanks, I'll take a look

[amaitland]

Closing this now as the originally reported issue has been resolved. Improving usability makes sense, so I've opened #2258 to track that.