Bug: ToolBar always using overflow menu whenever a scaled resolution set
Cormac Redmond
credmond at certak.com
Sun Dec 21 02:43:20 UTC 2025
Draft PR with proposed fix & tests:
https://github.com/openjdk/jfx/pull/2016/
On Sun, 21 Dec 2025 at 00:40, Cormac Redmond <credmond at certak.com> wrote:
> Hi,
>
> I want to re-raise this issue for discussion (Andy created a bug a while
> back: http://bugs.openjdk.org/browse/JDK-8366739, simple reproducer code
> is in the bug as well as previous mail in this thread).
>
> See the "x" variable from code from ToolBarSkin. The trailing 0001 is due
> to normal floating-point behavior, and is causing the x > length to be true
> when we don't want it. This must be happening in the wild quite a bit.
>
> [image: image.png]
>
> Exactly what is causing the bug, is easily reproducible in Plain Java. So
> is a fix, using a tolerance.
>
> public class Float {
> static void main() {
> double separatorLength = 10.4;
> double buttonLength = 99.2;
> double x = separatorLength + buttonLength;
> System.out.println("separatorLength: " + separatorLength);
> System.out.println("buttonLength: " + buttonLength);
> System.out.println("Sum: " + x);
> // Output: Sum: 109.60000000000001
>
> // Now for a potential fix.
>
> // This is the "length" variable value in ToolBarSkin, as per
> screenshot
> double length = 109.6;
>
> if(x > length) {
> System.out.println("BUG: x is regarded as greater than length,
> it should not be!");
> }
>
> // Create an epsilon, using scientific notation for 0.000000001
> final double EPS = 1e-9;
>
> // And change the comparison in ToolBarSkin from if(x > length) to:
> if (x - length > EPS) {
> // Won't happen now
> } else {
> System.out.println("FIX: with EPS tolerance, x is NOT greater
> than length.");
> }
> }
> }
> Full output, proving it works:
>
> separatorLength: 10.4
> buttonLength: 99.2
> Sum: 109.60000000000001
> BUG: x is regarded as greater than length, it should not be!
> FIX: with EPS tolerance, x is NOT greater than length.
>
>
> Some questions:
>
> - Is there any reason this would not be safe?
> - Should we centralise this (or whatever the final fix is) somewhere?
> Or are there already some utilities (I assume this sort of problem is
> commonplace)?
>
>
>
> Example of the bug appearing in the real-world:
> [image: image.png]
>
>
>
>
>
> Kind Regards,
> Cormac
>
> On Sat, 30 Aug 2025 at 01:20, Cormac Redmond <credmond at certak.com> wrote:
>
>> Hi,
>>
>> A variation of this bug still persists (JFX 25-ea+28).
>>
>> Run this code (125% display scaling, on Windows):
>>
>> public class ToolbarBugApp extends Application {
>>
>> @Override
>> public void start(Stage primaryStage) {
>> ToolBar tb = new ToolBar();
>> tb.getItems().addAll(
>> new Separator(Orientation.VERTICAL),
>> new Button("Create Schema")
>> );
>>
>> BorderPane bp = new BorderPane();
>> bp.setTop(new HBox(tb));
>> primaryStage.setScene(new Scene(bp, 600, 400));
>> primaryStage.show();
>> }
>>
>> public static void main(String[] args) {
>> launch(args);
>> }
>> }
>>
>> And you'll still see this:
>>
>> [image: image.png]
>>
>>
>>
>> Kind Regards,
>> Cormac
>>
>> On Thu, 24 Jul 2025 at 16:12, Kevin Rushforth <kevin.rushforth at oracle.com>
>> wrote:
>>
>>> https://bugs.openjdk.org/browse/JDK-8364049
>>>
>>>
>>> On 7/24/2025 7:15 AM, Kevin Rushforth wrote:
>>>
>>> This does look like a real bug. Thanks for filing it.
>>>
>>> Unfortunately one cannot attach screenshots on JBS submissions, so a
>>> text description will have to do.
>>>
>>>
>>> I have attached the two images to the bug. It will show up publicly,
>>> with a JDK bug ID, soon.
>>>
>>> -- Kevin
>>>
>>>
>>> On 7/23/2025 3:17 PM, Cormac Redmond wrote:
>>>
>>> I've a habit of finding non-bugs, so prefer to discuss it first to get
>>> some feedback (and/or to avoid duplicating known bugs), but I assume this
>>> is definitely an issue, so I created it on JBS now: 9078765...
>>>
>>> Unfortunately one cannot attach screenshots on JBS submissions, so a
>>> text description will have to do.
>>>
>>> Thanks!
>>>
>>>
>>> Kind Regards,
>>> Cormac
>>>
>>> On Wed, 23 Jul 2025 at 20:30, Andy Goryachev <andy.goryachev at oracle.com>
>>> wrote:
>>>
>>>> Do we have the JBS ticket filed for this issue?
>>>>
>>>>
>>>>
>>>> -andy
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
>>>> *From: *openjfx-dev <openjfx-dev-retn at openjdk.org> on behalf of Cormac
>>>> Redmond <credmond at certak.com>
>>>> *Date: *Tuesday, July 22, 2025 at 12:08
>>>> *To: *openjfx-dev at openjdk.org <openjfx-dev at openjdk.org>
>>>> *Subject: *Re: Bug: ToolBar always using overflow menu whenever a
>>>> scaled resolution set
>>>>
>>>> Any thoughts on this? It seems like a definite JavaFX bug with
>>>> hopefully a simple fix. Choosing any fractional scaled resolution may or
>>>> may not cause the issue. I also wonder what other controls may suffer from
>>>> the same issues.
>>>>
>>>>
>>>>
>>>> On Sat 19 Jul 2025, 19:01 Cormac Redmond, <credmond at certak.com> wrote:
>>>>
>>>> Hi,
>>>>
>>>>
>>>>
>>>> I've traced the bug down to a rounding error. See the below screenshot
>>>> in ToolBarSkin's getOverflowNodeIndex(double length).
>>>>
>>>>
>>>>
>>>> These two numbers are not equal, but should be. snapSizeX() ultimately
>>>> ends up grabbing getSnapScaleX(), whose value would be 1.25. If it's 1
>>>> (i.e., no scaling), we don't see this issue. If it's 1.25, we see this
>>>> rounding difference between the two numbers in this instance. If these two
>>>> numbers are not equal, the calling code mistakenly assumes the overflow box
>>>> is necessary.
>>>>
>>>>
>>>>
>>>>
>>>>
>>>> Can someone fix this?
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
>>>> Kind Regards,
>>>>
>>>> Cormac
>>>>
>>>>
>>>>
>>>> On Sat, 19 Jul 2025 at 18:33, Cormac Redmond <credmond at certak.com>
>>>> wrote:
>>>>
>>>> Confusingly, make the string longer, such as "Create Schema 123 123
>>>> 123":
>>>>
>>>>
>>>>
>>>> bp.setTop(new HBox(new ToolBar(new Button("Create Schema 123
>>>> 123 123"))));
>>>>
>>>>
>>>>
>>>> ...and the overflow doesn't appear (but still, anything between and
>>>> including 13-24, it does):
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
>>>> Kind Regards,
>>>>
>>>> Cormac
>>>>
>>>>
>>>>
>>>> On Sat, 19 Jul 2025 at 11:12, Cormac Redmond <credmond at certak.com>
>>>> wrote:
>>>>
>>>> Hi,
>>>>
>>>>
>>>>
>>>> There's a bug whenever using a ToolBar on Windows if you set your
>>>> resolution scale > 100% (which is quite common). E.g., 125%:
>>>>
>>>>
>>>>
>>>>
>>>>
>>>> E.g., this is what a ToolBar always renders if scale is 125%:
>>>>
>>>>
>>>>
>>>>
>>>>
>>>> As compared to what you'd expect (scale set to normal/100%):
>>>>
>>>>
>>>>
>>>>
>>>>
>>>> Very easy to reproduce the above, set your scale to 125% and run this:
>>>>
>>>>
>>>>
>>>> public class ToolbarBugApp extends Application {
>>>>
>>>>
>>>> @Override
>>>> public void start(Stage primaryStage) {
>>>> BorderPane bp = new BorderPane();
>>>> // Wrapping in HBox and using button with 13+ chars causes bug
>>>> bp.setTop(new HBox(new ToolBar(new Button("Create Schema"))));
>>>> // BUG
>>>> // bp.setTop(new ToolBar(new Button("Create Schema"))); // NO
>>>> BUG (no HBox)
>>>> // bp.setTop(new HBox(new ToolBar(new Button("Create
>>>> Schem")))); // NO BUG (12 chars)
>>>> primaryStage.setScene(new Scene(bp, 600, 400));
>>>> primaryStage.show();
>>>> }
>>>>
>>>> public static void main(String[] args) {
>>>> launch(args);
>>>> }
>>>> }
>>>>
>>>>
>>>>
>>>> As per the comments, this bug appears to happen when your ToolBar is
>>>> wrapped in a HBox and contains a Button that has 13+ characters, for
>>>> example. This is quite a serious bug, in my opinion.
>>>>
>>>>
>>>>
>>>> I believe this is present in JFX 24 and the JFX 25 master branch.
>>>>
>>>>
>>>>
>>>>
>>>>
>>>> Kind Regards,
>>>>
>>>>
>>>>
>>>> *Cormac Redmond*
>>>>
>>>> Software Engineer, Certak Ltd.
>>>>
>>>>
>>>>
>>>> e: credmond at certak.com | m: +353 (0) 86 268 2152 | w: www.certak.com
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
>>>
>>>
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