Is there some option that can be added to project.xml to avoid the app window from being resized ?
I remember there was even a way back in the day to make the window without a frame and also starting full screen. But I forgot…
Is this possible now, to make the application window non-resizable ?
Should be <window resizable="false" /> 
Thanks singmajesty, I was using resizeable=“false”, extra A for no reason. Driving myself insane, wondering if I was making the option up… 
For extra stuffs you can do in project file take a look at this: http://www.openfl.org/learn/resources/command-line-tools/project-files/xml-format/
Thanks Tommy, I actually went through that page before asking. Only thing is I was browser searching for the word “resizeAble”…
btw: Up from the Ground, looked great.
Good to know that you have solved the problem! And thanks for looking at my project! Well its not being developed anymore but still thanks a lot 