Strange line breaking behavior when using the SWT.WRAP flag in a SWT Label

[selundqma]

Describe the bug
Strange line breaking behavior when using the SWT.WRAP flag in a SWT Label and the text contains Swedish characters (åäö).
Seen so far only on Windows (11). I expected the wrapping to happen only on white spaces and not on "special characters" like åäö (or similar extra chars in other languages). Could it be that all the line breaking functionality is handled by OS calls and that we have no control over how it happens in the Java code? Or, is it possible to understand why the line break happens?

Environment
JRE/JDK version 21.0.4.7.1
Eclipse 4.31 (2023-03)

Screenshots
Please see screenshots for clarification. The screenshot with the arrows shows where the unwanted line break happens. Taken from Windows 11.

The screenshot without any arrows where it looks ok is taken from MacOS Sonoma.

[laeubi]

Sadly WRAP is not really specified the API only says

eclipse.platform.swt/bundles/org.eclipse.swt/Eclipse SWT/common/org/eclipse/swt/SWT.java

Lines 1543 to 1554 in 90111e3

	/**
	* Style constant for automatic line wrap behavior (value is 1<<6).
	* <p><b>Used By:</b></p>
	* <ul>
	* <li><code>Button</code></li>
	* <li><code>Label</code></li>
	* <li><code>Text</code></li>
	* <li><code>ToolBar</code></li>
	* <li><code>Spinner</code></li>
	* </ul>
	*/
	public static final int WRAP = 1 << 6;

so all one can expect is that some wrapping is performed but not how exactly.

[mickaelistria]

Seen so far only on Windows (11)

Do other win32-API based software show the same issue?

[selundqma]

I was hoping to get hold of someone who knows about the "strange" line breaking behavior. I am sadly not as educated in this matter to answer any technical questions back.

[selundqma]

Seems to work better in Text and StyledText components. We will take that road instead of using the Label class.