(Some) Dialogs are smaller than expected

[akoch-yatta]

Description
Some dialogs will be smaller, e.g. the workspace selection dialog or the windows defender dialog

Reproduction
The described setup is not testable with a Runtime Workspace and must be setup correctly, but can happen easily in real scenarios because those dialogs are not opened then. There are probably other dialogs affected similarly in Runtime as well.

1. Configure monitor setup as: Primary 150%, secondary 100%
2. Very Important: Open the File Explorer and move it to the secondary monitor
3. Start the latest I-Build from the File Explorer

Expected Behavior
The text should not be wrapped unnecessarily (in workspace selection dialog) and it should be fully readable (windows defender dialog)

Necessary configuration:
monitor specific scaling on a 150% primary monitor

Additional knowledge
The reason is that the size of the Shell is originally calculated for the 100% zoom, then it will be moved to the primary monitor with 150%. The OS is giving us new bounds that are exactly scaling by factor 1.5. But as the font is updated as well and a text with a 150% font is not necessarily exactly 1.5 times the width of the text rendered a 100% font, unexpected text wrapping or a different overall height is the result.

One possible solution is to not use the bounds provided by the OS in Control#WM_DPICHANGED, but call computeSize on the Shell and set this bounds.

[arunjose696]

I created a snippet to reproduce this issue.

public class SimpleDialog {
    public static void main(String[] args) {
        Display display = new Display();
        Shell shell = new Shell(display);
        shell.setLayout(new RowLayout(SWT.VERTICAL));
        Label message = new Label(shell, SWT.LEFT);
        message.setText("the numbers one two three and in the next line \n four five six seven eight nine ten");
        Label message1 = new Label(shell, SWT.LEFT);
        message1.setText("the numbers one two three and in the next line \n four five six seven eight nine ten");
        shell.pack();
        shell.open();

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

When running this snippet with a 100% primary monitor and moving to a monitor with 150% zoom would result in incorrect text wrapping as mentioned in the issue

One possible solution is to not use the bounds provided by the OS in Control#WM_DPICHANGED, but call computeSize on the Shell and set this bounds.

Tried out the suggested approach, this approach only works if the shells are never resized after creation. If the shell is resized manually or programmatically, computeSize will still return the original size of the shell/control, ignoring any resizing that has occurred.