Table flashes in white on column moving when in dark theme

[jose-vasco]

Hello! We are experiencing the whole table flashing when one starts to move table columns on dark theme on macOS (latest SWT - though we had seen this behavior in previous versions too, - and at least from Big Sur on).

In order to reproduce this, one should set table columns of a TreeViewer as moveable, and make the app useSystemAppearance while having the macOS in dark theme. As soon as one grabs the header of a column to move it, the whole table will get its background set to white. It reverts to its original look at dropping the column in any place. Additionally, this seems not to happen in M1 machines.

[lshanmug]

Can you please provide a snippet to reproduce the issue?

[buchen]

@jose-vasco Have you made any progress?

My open source project Portfolio Performance is a RCP Eclipse application. I not only experience this when moving the tables, but also when expanding or collapsing trees. See the video below.

I am running: Eclipse 2024-12 = Eclipse 4.34 = SWT 3.128.0.v20241113-2009

Bildschirmaufnahme.2024-12-29.um.18.54.27.mp4

This is how the tree is created (there are multiple trees within the application)

@lshanmug I am aware that this is not a snippet. Any hints where to look? It does not happen in Eclipse itself (for example in the "Problem" pane when grouped by problem type). How are the trees created differently there?

[buchen]

@lshanmug The problem starts to show when adding this line:

treeViewer.getTree().setLinesVisible(true);

I can confirm that the problem goes away in my e4 application when commenting out this line.

Here is a simple example to reproduce the problem. It is based on the default E4 Application created by the wizard. I then activate the dark theme and add a tree viewer.

com.example.e4.rcp.zip

Bildschirmaufnahme.2024-12-30.um.08.50.10.mp4

Please ignore the "Workbench has not been created yet" errors. The reasons is that this example is using the default macOS dark theme which in turn uses a color provider not available for a pure E4 application.

SamplePart (from the E4 Application)

package com.example.e4.rcp.parts;

import java.util.Arrays;
import java.util.List;

import org.eclipse.e4.ui.di.Focus;
import org.eclipse.e4.ui.di.Persist;
import org.eclipse.e4.ui.model.application.ui.basic.MPart;
import org.eclipse.jface.viewers.ITreeContentProvider;
import org.eclipse.jface.viewers.TreeViewer;
import org.eclipse.jface.widgets.TextFactory;
import org.eclipse.swt.SWT;
import org.eclipse.swt.layout.GridData;
import org.eclipse.swt.layout.GridLayout;
import org.eclipse.swt.widgets.Composite;

import jakarta.annotation.PostConstruct;
import jakarta.inject.Inject;

public class SamplePart {

	private TreeViewer treeViewer;

	@Inject
	private MPart part;

	@PostConstruct
	public void createComposite(Composite parent) {
		parent.setLayout(new GridLayout(1, false));

		TextFactory.newText(SWT.BORDER) //
				.message("Enter text to mark part as dirty") //
				.onModify(e -> part.setDirty(true)) //
				.layoutData(new GridData(GridData.FILL_HORIZONTAL))//
				.create(parent);

		treeViewer = new TreeViewer(parent);
		
		treeViewer.getTree().setLinesVisible(true);

		treeViewer.setContentProvider(new TreeContentProvider());
		treeViewer.setInput(new Node("Root", Arrays.asList( //
				new Node("Item 1", Arrays.asList(new Node("Subitem 1", Arrays.asList()))), //
				new Node("Item 2", Arrays.asList(new Node("Subitem 2", Arrays.asList()))), //
				new Node("Item 3", Arrays.asList(new Node("Subitem 3", Arrays.asList()))), //
				new Node("Item 4", Arrays.asList(new Node("Subitem 4", Arrays.asList()))), //
				new Node("Item 5", Arrays.asList(new Node("Subitem 5", Arrays.asList()))))));
		treeViewer.getTree().setLayoutData(new GridData(GridData.FILL_BOTH));
	}

	@Focus
	public void setFocus() {
		treeViewer.getTree().setFocus();
	}

	@Persist
	public void save() {
		part.setDirty(false);
	}
}

class Node {
	private final String name;
	private final List<Node> children;

	public Node(String name, List<Node> children) {
		this.name = name;
		this.children = children;
	}

	public String getName() {
		return name;
	}

	public List<Node> getChildren() {
		return children;
	}
	
	public String toString() {
		return name;
	}
}

class TreeContentProvider implements ITreeContentProvider {
	@Override
	public boolean hasChildren(Object element) {
		return !((Node) element).getChildren().isEmpty();
	}

	@Override
	public Object getParent(Object element) {
		return null;
	}

	@Override
	public Object[] getElements(Object inputElement) {
		return ((Node) inputElement).getChildren().toArray();
	}

	@Override
	public Object[] getChildren(Object parentElement) {
		return ((Node) parentElement).getChildren().toArray();
	}
}

plugin.xml with the dark theme

<?xml version="1.0" encoding="UTF-8"?>
<?eclipse version="3.4"?>
<plugin>

   <extension
         id="product"
         point="org.eclipse.core.runtime.products">
      <product
            application="org.eclipse.e4.ui.workbench.swt.E4Application"
            name="com.example.e4.rcp">
         <property
               name="cssTheme"
               value="com.example.theme.dark">
         </property>         
      </product>
   </extension>
   
      <extension
         point="org.eclipse.e4.ui.css.swt.theme">
      <theme
            basestylesheeturi="css/dark_mac.css"
            id="com.example.theme.dark"
            label="Dark Theme"
            os="macosx">
      </theme>
   </extension>

</plugin>

dark_mac.css

@import url("platform:/plugin/org.eclipse.ui.themes/css/e4-dark_mac.css");