Why are some applications blurred on a "scaled" high res 4K screen?

Hello

I have just installed a high resolution 27" 4K screen. In order to make my text large enough to be readable I have had do set my Windows Scaling to 200%.

This means that the UI of many applications that I use (e.g. MLO, Xara Designer Pro X10) are blurred. Technically why is this? It doesn't happen on all applications (e.g. ms Office, Photoshop CC 2015 are fine).

I have discovered that if you right click on the link to the application in question, under compatibility you can tick "Disable display scaling at high DPI settings". This stops the blurring, but it makes most of the UI including menu text become very small. Worse not ALL parts of the UI have now shrunk, and some menu options can become unusable.

Do these applications need to be re-written from scratch. Will the text in the application's UI have been defined in stupid units (e.g. pixels)?

What do we users need to demand from our application developers in order to get the problem cured?

J

It happens because those applications do not support DPI aware interfaces. So what happens is they are resized to the scale you set. But yes, the applications are set to static pixel values, and it is up to the developer to fix it.

If the application is still in development, contact them and demand a fix for DPI scaling.