Chad,
I’d like to better understand why you encountered this problem to begin with.
In the past we’ve only had difficulties on KDE when the user configured
fractional scaling in System Settings. If the global scale in Display Settings
is 200% you should be fine. If it’s something like 175% then JavaFX will
misbehave. As Christopher pointed out the details are in
https://bugs.openjdk.org/browse/JDK-8326428.
I would like to reproduce your setup. Which distro and version are you running?
And what value are you using for global scale in System Settings > Display
Configuration?
At least in the past this hasn’t been due to Wayland vs. Xorg. When fractional
scaling is in effect KDE plays games with some legacy settings which JavaFX
responds to (the fix for JDK-8326428 is to reduce their priority). They’re the
GDK_SCALE environment variable and an internal Gnome setting:
gsettings get org.gnome.desktop.interface scaling-factor
It’s also possible you’re running into some new issue not covered by
JDK-8326428. That windows are being misplaced on your system makes me think
something more is going on. And we should be able to get that right whether
we’re a Wayland client or not.
Thanks,
Martin
> On Nov 22, 2025, at 6:23 AM, Chad Preisler <[email protected]> wrote:
>
> Thanks for the suggestions. Both suggestions work and look good. Here are
> some observations from my testing.
>
> glass.gtk.uiScale:
> - Looks great.
> - Allows for decimal values.
> - On my 2k monitor 1.25 looked best.
> - If the KDE "Scaled by the system" setting is turned on, then using this
> setting makes the scene larger than expected.
>
> export GDK_SCALE=2:
> - Looks great.
> - It appears it only allows whole numbers, and 2.0 was a little too large for
> my taste.
> - If the KDE "Scaled by the system" setting is turned on, then using this
> setting makes the scene larger than expected.
>
> Scaled by the system:
> - Looks great
> - Looks like it scales it about 1.25
> - Netbeans looks pretty good with this setting, but I needed to set
> --fontsize 14 in the netbeans.conf file. Netbeans looks a little better when
> it's scaled using uiScale and flatlaf settings.
>
> Under all settings when the application started up it appeared in the top
> left corner of the first screen. Pop-ups in the application were not centered
> and were up and off the upper left corner of the scene.
>
> I guess until JavaFX can be a pure wayland client I'm personally going to
> stick with the "Scaled by the system" setting. I guess if I ever bundle and
> deploy my app I would recommend users to do the same.
>
> On Fri, Nov 21, 2025 at 4:05 PM Christopher Schnick <[email protected]
> <mailto:[email protected]>> wrote:
>> I think this was the issue I mentioned:
>> https://bugs.openjdk.org/browse/JDK-8326428
>>
>> On 21/11/2025 23:00, Kevin Rushforth wrote:
>> > Another workaround is to set the "GDK_SCALE" environment variable, for
>> > example:
>> >
>> > export GDK_SCALE=2
>> >
>> > I found the following enhancement request in our bug backlog
>> > requesting automatic detection of the screen scale:
>> >
>> > https://bugs.openjdk.org/browse/JDK-8238077
>> >
>> > I changed the title to be more reflective of this and reassigned the
>> > bug. It's something that we could consider implementing if it isn't
>> > too difficult.
>> >
>> > -- Kevin
>> >
>> >
>> > On 11/21/2025 11:33 AM, Christopher Schnick wrote:
>> >> You are probably looking for glass.gtk.uiScale
>> >>
>> >> I think I reported a while ago that the automatic scale detection for
>> >> KDE is not working, but apparently there wasn't an easy API
>> >> replacement available.
>> >>
>> >> On 21/11/2025 18:15, Chad Preisler wrote:
>> >>> Hello,
>> >>>
>> >>> When I run my JavaFX (using JFX25) application on KDE Plasma using
>> >>> Wayland the fonts are incredibly small. How can I scale the
>> >>> application so that things are not so tiny?
>> >>>
>> >>> FYI: I had a similar issue with Netbeans. I know it's different
>> >>> because it is Swing. I was able to get Netbeans to look good with
>> >>> the following settings.
>> >>>
>> >>> -J-Dsun.java2d.uiScale=2 -J-Dflatlaf.uiScale=0.75
>> >>>
>> >>> Is there something similar I can do for JavaFX?
>> >>>
>> >>> Thanks,
>> >>> Chad
>> >>>
>> >>>
>> >
