Scale Table.GRID_WIDTH by zoom level instead of using fixed pixels

[ShahzaibIbrahim]

The Table.GRID_WIDTH constant specifies the extra width added to a table item when lines between columns are visible (lineVisible = true). This accounts for the space taken by the grid line. Previously, it was defined as a fixed
pixel value, which appeared too small on high-DPI monitors.

This change redefines GRID_WIDTH in points and scales it to pixels based on the current zoom level. At 100% zoom this results in 2px instead of 1px, which is visually negligible but ensures consistency by keeping all constants defined in points and scaled according to zoom level.

How to Test

• Run the following snippet on a Primary monitor with 250% zoom
• You will notice extra pixel in the width compared to previous state.

import org.eclipse.swt.*;
import org.eclipse.swt.layout.*;
import org.eclipse.swt.widgets.*;

public class LinesVisibleTableExample {

    public static void main (String [] args) {
        System.setProperty("swt.autoScale", "quarter");
        System.setProperty("swt.autoScale.updateOnRuntime", "true");
        
        Display display = new Display ();
        Shell shell = new Shell (display);
        shell.setText("SWT Table Example");
        shell.setLayout(new FillLayout());

        // Create table
        final Table table = new Table(shell, SWT.BORDER | SWT.FULL_SELECTION);
        table.setHeaderVisible(true);
        table.setLinesVisible(true);

        // Create columns
        String[] titles = { "Level 0", "Level 1", "Level 2", "Level 3" };
        for (String title : titles) {
            TableColumn column = new TableColumn(table, SWT.NONE);
            column.setText(title);
            column.setWidth(100);
        }

        // Fill table with hierarchical-like data
        for (int i = 0; i < 4; i++) {
            for (int j = 0; j < 4; j++) {
                for (int k = 0; k < 4; k++) {
                    for (int l = 0; l < 4; l++) {
                        TableItem item = new TableItem(table, SWT.NONE);
                        item.setText(new String[] {
                            "TableItem (0) -" + i,
                            "TableItem (1) -" + j,
                            "TableItem (2) -" + k,
                            "TableItem (3) -" + l
                        });
                    }
                }
            }
        }

        shell.setSize(450, 250);
        shell.open();
        while (!shell.isDisposed()) {
            if (!display.readAndDispatch()) display.sleep();
        }
        display.dispose();
    }
}

[github-actions]

Test Results

   546 files  ±0     546 suites  ±0   33m 10s ⏱️ + 2m 27s
 4 426 tests ±0   4 409 ✅ ±0   17 💤 ±0  0 ❌ ±0 
16 750 runs  ±0  16 623 ✅ ±0  127 💤 ±0  0 ❌ ±0 

Results for commit a3526b1. ± Comparison against base commit 9bf4caf.

♻️ This comment has been updated with latest results.

[akoch-yatta]

Changes are very similar to #2443. Changes look sound and I didn't find any problems when testing the changes.