How to switch off HiDPI scaling for individual applications

[kybos]

I use the HiDPI global setting for my 4k monitor. This works pretty well for most applications.
One of the problematic ones is NetBeans - here Cinnamon scales the fonts OK, but this breaks the UI in many places as the UI elements are not adjusted accordingly. Starting with version 9, NetBeans supports UI scaling using the GDK_SCALE env variable, so with GDK_SCALE = 2 the UI elements are scaled correctly, but then the fonts are much too big and break the UI again (being scaled both by Netbeans and Cinnamon, obviously).
GDK_DPI_SCALE and netbeans --font-size have no effect on this.

So my question is: How can I switch off the Cinnamon scaling for this app only?

Thanks,
Kybos

[aknickolai]

I don's use Cinnamon, but these are the parameters that I muck with to get GTK scaling correct in KDE are:

GDK_SCALE=2
GDK_DPI_SCALE=0.5

The first line doubles the scaling for all elements, the second line removes the scaling for fonts.

[kybos]

Yes, that's the standard GTK3 way, but unfortunately, as I wrote above, GDK_DPI_SCALE is not understood by NetBeans...

[aknickolai]

Whoops, sorry I missed that...

Did you try launching the program with GDK_SCALE=1 or GDK_SCALE=0.5?

I can't remember what Cinammon's default HDPI multiplier is, but if you undo that scaling right multiplier with GDK_SCALE for netbeans it should launch un-scaled.

Also, take a look at:

http://wiki.netbeans.org/FaqFontSize

[kybos]

Yes, no luck with all that, unfortunately...
Cinnamons HiDPI multiplier is 2, by the way.

Thanks anyway.

[aknickolai]

I stumbled across this the other day and remembered this post!

https://github.com/kaueraal/run_scaled

It does exactly what you are looking for. I use it to play Wesnoth (no HiDPI support) on a 4k screen.

[kybos]

Thanks, I know that script, it's the last resort for apps that do not scale at all in 4k (like Audacity). But it does not help with the inconsistent scaling in NetBeans.

I found a very good solution for my problem in this post:
https://issues.apache.org/jira/browse/NETBEANS-765

In short:
1. Install latest NetBeans (currently 11)
2. Install latest JDK (currently 11)
3. Install Darcula LAF add-on (from github)
4. Start in bash with GDK_SCALE=2 netbeans

Not only is the scaling correct for all UI elements and fonts, but it even looks really good...