[Grid] Implement frozen first column in SWT (RCP), fixes #695

examples/org.eclipse.nebula.snippets/src/org/eclipse/nebula/snippets/grid/GridFrozenFirstColumnSnippet.java

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+/*******************************************************************************
+ * Copyright (c) 2026 Eclipse Nebula contributors.
+ *
+ * This program and the accompanying materials
+ * are made available under the terms of the Eclipse Public License 2.0
+ * which accompanies this distribution, and is available at
+ * https://www.eclipse.org/legal/epl-2.0/
+ *
+ * SPDX-License-Identifier: EPL-2.0
+ *******************************************************************************/
+package org.eclipse.nebula.snippets.grid;
+
+import org.eclipse.nebula.widgets.grid.Grid;
+import org.eclipse.nebula.widgets.grid.GridColumn;
+import org.eclipse.nebula.widgets.grid.GridColumnGroup;
+import org.eclipse.nebula.widgets.grid.GridEditor;
+import org.eclipse.nebula.widgets.grid.GridItem;
+import org.eclipse.swt.SWT;
+import org.eclipse.swt.events.SelectionAdapter;
+import org.eclipse.swt.events.SelectionEvent;
+import org.eclipse.swt.layout.GridData;
+import org.eclipse.swt.layout.GridLayout;
+import org.eclipse.swt.widgets.Composite;
+import org.eclipse.swt.widgets.Control;
+import org.eclipse.swt.widgets.Display;
+import org.eclipse.swt.widgets.Label;
+import org.eclipse.swt.widgets.Shell;
+import org.eclipse.swt.widgets.Text;
+
+/**
+ * Demonstrates a frozen first column in {@link Grid}.
+ *
+ * <p>Three scenarios are shown stacked top-to-bottom:</p>
+ * <ul>
+ *   <li><b>Plain frozen column</b> &mdash; the first column stays visible while
+ *       horizontal scrolling moves the rest of the columns behind it. The first
+ *       column is also editable to verify {@link GridEditor} positioning.</li>
+ *   <li><b>Frozen tree column with expand/collapse toggles</b> &mdash; the
+ *       frozen first column is also the tree column. Scroll horizontally so
+ *       the rest of the grid moves behind the frozen column, then click the
+ *       toggle on a parent row: the row should still expand or collapse. This
+ *       is the case that motivated the original bug report &mdash; without
+ *       the freeze-aware hit-testing, toggle clicks were routed to the
+ *       scrolled column underneath the overlay and the toggle appeared
+ *       unresponsive.</li>
+ *   <li><b>Frozen column inside a column group</b> &mdash; the frozen first
+ *       column shares a {@link GridColumnGroup} with scrollable columns. This
+ *       configuration is unsupported; the grid logs a one-time warning to
+ *       stderr and degrades gracefully by omitting the group header from the
+ *       frozen overlay.</li>
+ * </ul>
+ */
+public class GridFrozenFirstColumnSnippet {
+
+	private static final int COLUMN_COUNT = 8;
+	private static final int ROW_COUNT = 30;
+
+	public static void main(String[] args) {
+		Display display = new Display();
+		Shell shell = new Shell(display);
+		shell.setText("Grid - Frozen First Column");
+		shell.setLayout(new GridLayout(1, false));
+		shell.setSize(800, 720);
+
+		createSimpleSection(shell);
+		createTreeSection(shell);
+		createGroupSection(shell);
+
+		shell.open();
+		while (!shell.isDisposed()) {
+			if (!display.readAndDispatch()) {
+				display.sleep();
+			}
+		}
+		display.dispose();
+	}
+
+	private static void createSimpleSection(Composite parent) {
+		Composite section = new Composite(parent, SWT.NONE);
+		section.setLayout(new GridLayout(1, false));
+		section.setLayoutData(new GridData(SWT.FILL, SWT.FILL, true, true));
+
+		Grid grid = new Grid(section, SWT.BORDER | SWT.V_SCROLL | SWT.H_SCROLL);
+		grid.setHeaderVisible(true);
+		grid.setLinesVisible(true);
+		grid.setLayoutData(new GridData(SWT.FILL, SWT.FILL, true, true));
+
+		GridColumn frozen = new GridColumn(grid, SWT.NONE);
+		frozen.setText("Name (frozen)");
+		frozen.setWidth(160);
+		frozen.setFixed(true);
+
+		for (int c = 1; c < COLUMN_COUNT; c++) {
+			GridColumn column = new GridColumn(grid, SWT.NONE);
+			column.setText("Column " + c);
+			column.setWidth(120);
+		}
+
+		for (int r = 0; r < ROW_COUNT; r++) {
+			GridItem item = new GridItem(grid, SWT.NONE);
+			item.setText(0, "Row " + (r + 1));
+			for (int c = 1; c < COLUMN_COUNT; c++) {
+				item.setText(c, "r" + (r + 1) + "c" + c);
+			}
+		}
+
+		attachFirstColumnEditor(grid);
+	}
+
+	private static void createTreeSection(Composite parent) {
+		Composite section = new Composite(parent, SWT.NONE);
+		section.setLayout(new GridLayout(1, false));
+		section.setLayoutData(new GridData(SWT.FILL, SWT.FILL, true, true));
+
+		Label caption = new Label(section, SWT.WRAP);
+		caption.setText("Frozen tree column: scroll horizontally with the bottom scrollbar, "
+				+ "then click an expand/collapse toggle on the frozen column. "
+				+ "Without freeze-aware hit-testing, the click would land on the column "
+				+ "underneath the overlay and the toggle would appear unresponsive.");
+		caption.setLayoutData(new GridData(SWT.FILL, SWT.BEGINNING, true, false));
+
+		Grid grid = new Grid(section, SWT.BORDER | SWT.V_SCROLL | SWT.H_SCROLL);
+		grid.setHeaderVisible(true);
+		grid.setLinesVisible(true);
+		grid.setLayoutData(new GridData(SWT.FILL, SWT.FILL, true, true));
+
+		GridColumn frozen = new GridColumn(grid, SWT.NONE);
+		frozen.setText("Tree (frozen)");
+		frozen.setWidth(180);
+		frozen.setTree(true);
+		frozen.setFixed(true);
+
+		for (int c = 1; c < COLUMN_COUNT; c++) {
+			GridColumn column = new GridColumn(grid, SWT.NONE);
+			column.setText("Column " + c);
+			column.setWidth(120);
+		}
+
+		for (int p = 0; p < 5; p++) {
+			GridItem parentItem = new GridItem(grid, SWT.NONE);
+			parentItem.setText(0, "Parent " + (p + 1));
+			for (int c = 1; c < COLUMN_COUNT; c++) {
+				parentItem.setText(c, "p" + (p + 1) + "c" + c);
+			}
+			for (int ch = 0; ch < 3; ch++) {
+				GridItem child = new GridItem(parentItem, SWT.NONE);
+				child.setText(0, "Child " + (ch + 1));
+				for (int c = 1; c < COLUMN_COUNT; c++) {
+					child.setText(c, "p" + (p + 1) + "ch" + (ch + 1) + "c" + c);
+				}
+			}
+			parentItem.setExpanded(p == 0);
+		}
+	}
+
+	private static void createGroupSection(Composite parent) {
+		Composite section = new Composite(parent, SWT.NONE);
+		section.setLayout(new GridLayout(1, false));
+		section.setLayoutData(new GridData(SWT.FILL, SWT.FILL, true, true));
+
+		Grid grid = new Grid(section, SWT.BORDER | SWT.V_SCROLL | SWT.H_SCROLL);
+		grid.setHeaderVisible(true);
+		grid.setLinesVisible(true);
+		grid.setLayoutData(new GridData(SWT.FILL, SWT.FILL, true, true));
+
+		GridColumnGroup group = new GridColumnGroup(grid, SWT.NONE);
+		group.setText("Spans frozen + scrolled (unsupported, warns once)");
+
+		GridColumn frozen = new GridColumn(group, SWT.NONE);
+		frozen.setText("Name (frozen)");
+		frozen.setWidth(160);
+		frozen.setFixed(true);
+
+		GridColumn inGroup = new GridColumn(group, SWT.NONE);
+		inGroup.setText("Group col");
+		inGroup.setWidth(120);
+
+		for (int c = 2; c < COLUMN_COUNT; c++) {
+			GridColumn column = new GridColumn(grid, SWT.NONE);
+			column.setText("Column " + c);
+			column.setWidth(120);
+		}
+
+		for (int r = 0; r < ROW_COUNT; r++) {
+			GridItem item = new GridItem(grid, SWT.NONE);
+			for (int c = 0; c < COLUMN_COUNT; c++) {
+				item.setText(c, "r" + (r + 1) + "c" + c);
+			}
+		}
+	}
+
+	private static void attachFirstColumnEditor(Grid grid) {
+		final GridEditor editor = new GridEditor(grid);
+		editor.grabHorizontal = true;
+		grid.addSelectionListener(new SelectionAdapter() {
+			@Override
+			public void widgetSelected(SelectionEvent e) {
+				Control old = editor.getEditor();
+				if (old != null) {
+					old.dispose();
+				}
+				GridItem[] selection = grid.getSelection();
+				if (selection.length == 0) {
+					return;
+				}
+				GridItem item = selection[0];
+				Text text = new Text(grid, SWT.NONE);
+				text.setText(item.getText(0));
+				text.selectAll();
+				text.setFocus();
+				text.addListener(SWT.FocusOut, ev -> {
+					item.setText(0, text.getText());
+					text.dispose();
+				});
+				editor.setEditor(text, item, 0);
+			}
+		});
+	}
+}

widgets/grid/org.eclipse.nebula.widgets.grid.test/pom.xml

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+<?xml version="1.0" encoding="UTF-8"?>
+<project xmlns="http://maven.apache.org/POM/4.0.0"
+	xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+	xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
+	<modelVersion>4.0.0</modelVersion>
+
+	<parent>
+		<groupId>org.eclipse.nebula</groupId>
+		<artifactId>grid</artifactId>
+		<version>1.1.0-SNAPSHOT</version>
+	</parent>
+
+	<artifactId>org.eclipse.nebula.widgets.grid.test</artifactId>
+	<version>0.4.0-SNAPSHOT</version>
+	<packaging>eclipse-test-plugin</packaging>
+
+	<!--
+		The other *_Test classes in this bundle (Grid_Test, GridItem_Test,
+		GridColumn_Test, GridColumnGroup_Test) date back to ~2010 and have
+		been bit-rotting in the IDE-only .launch configuration ever since:
+		they target an old SWT/JFace, an old Mockito (1.8.4), and assert
+		behaviour that has changed multiple times upstream. Restoring them
+		is a worthy effort but orthogonal to the frozen-first-column work
+		this bundle was wired into Maven for. Until that stabilisation
+		happens, only the freeze tests are run from the build so the
+		feature gets real CI protection without lighting up unrelated rot.
+	-->
+	<build>
+		<plugins>
+			<plugin>
+				<groupId>org.eclipse.tycho</groupId>
+				<artifactId>tycho-surefire-plugin</artifactId>
+				<version>${tycho-version}</version>
+				<configuration>
+					<includes>
+						<include>**/GridFixedColumn_Test.java</include>
+					</includes>
+				</configuration>
+			</plugin>
+		</plugins>
+	</build>
+
+</project>