Bug 529377

Description Lucas Koehler 2018-01-03 09:52:56 EST

Created attachment 272107 [details]
Eclipse project containing the example class and a target platform that uses the 4.7 update site

When using a ScrolledComposite that contains another ScrolledComposite within its content, the outer ScrolledComposite cannot be scrolled when the inner one has a hidden scroll bar and the mouse pointer is over the inner composite.

Example:
Outer ScrolledComposite A is configured for vertical scrolling and contains Composite B and ScrolledComposite C.
ScrolledComposite C is also configured for vertical scrolling.
In the application, A's scrollbar is shown and C's is hidden.
When I now try to scroll while the mouse cursor is over A, the scrolling does not work. When the cursor is over B or A's scroll bar, everything works as expected.

I tested this in a RCP application and small sample application in Oxygen.
Below you find the code of the sample application.
Alternatively, I attached a small sample project with a target definition that loads Eclipse RCP (and thereby SWT) from the Oxygen Update site.

The blue composite is the scroll composite with the hidden scroll bar.

I tested this on Ubuntu 17.04 and my GTK version is 3.22.11-0ubuntu3
I created the sample application after seeing Bug 474459. Maybe it's a related issue.



import org.eclipse.jface.layout.GridDataFactory;
import org.eclipse.jface.layout.GridLayoutFactory;
import org.eclipse.swt.SWT;
import org.eclipse.swt.custom.ScrolledComposite;
import org.eclipse.swt.layout.FillLayout;
import org.eclipse.swt.widgets.Composite;
import org.eclipse.swt.widgets.Display;
import org.eclipse.swt.widgets.Shell;

public class ScrolledCompositeExample {
	public static void main(String[] args) {
		Display display = new Display();

		Shell shell = new Shell(display);
		shell.setLayout(new FillLayout());

		final ScrolledComposite scrollComposite = new ScrolledComposite(shell, SWT.V_SCROLL | SWT.BORDER);

		final Composite content = new Composite(scrollComposite, SWT.NONE);
		GridLayoutFactory.swtDefaults().numColumns(2).applyTo(content);

		Composite left = new Composite(content, SWT.BORDER);
		left.setSize(100, 100);
		left.setBackground(Display.getDefault().getSystemColor(SWT.COLOR_GREEN));
		ScrolledComposite right = new ScrolledComposite(content, SWT.V_SCROLL | SWT.BORDER);
		right.setBackground(Display.getDefault().getSystemColor(SWT.COLOR_BLUE));
		GridDataFactory.fillDefaults().grab(true, true).applyTo(right);
		right.setLayout(new FillLayout());

		scrollComposite.setContent(content);
		scrollComposite.setExpandVertical(true);
		scrollComposite.setExpandHorizontal(true);
		scrollComposite.setMinHeight(600);

		shell.setSize(400, 400);
		shell.open();

		while (!shell.isDisposed()) {
			if (!display.readAndDispatch()) {
				display.sleep();
			}
		}
		display.dispose();
	}

}