Property change is propagated too far (even when the value remains the same)

[Justyna-JustCode]

openSUSE Leap 15.4
Slint 1.5 + Rust

Minimal example:

export component MainWindow inherits Window {
    property<bool> is-portrait: self.width < self.height;

    if self.is-portrait: Rectangle {
        width: 30%; height: 30%;
        background: red;

        init => { debug("Red rectangle created"); }
    }
    if !self.is-portrait: Rectangle {
        width: 30%; height: 30%;
        background: green;

        init => { debug("Green rectangle created"); }
    }
}

I expected that items would only be re-created when the orientation actually changes (i.e., when is-portrait is changed from false to true or from true to false). Still, in reality, I see the debug log ("... rectangle created") every time I resize the window, even when orientation stays the same (and a rectangle of a given color remains visible).

[ogoffart]

Thanks for the bug report.
This is actually a duplicate of #3953
So I'm closing this bug as duplicated.
But thanks anyway for taking the time to report the bug with a nice testcase.

[Justyna-JustCode]

Thanks! I tried to find any existing issues, but it seems I failed 😉
I just wanted to mention (since the other issue is mentioning conditional elements strictly) that it seems that conditional elements are not required for the bug to occur.

I also checked it in this configuration:

    Rectangle {
        width: 30%; height: 30%;
        background: root.is-portrait ? red : green;

        function on-is-portrait-changed(is-portrait: bool, returnValue: float) -> float {
            debug("Is portrait:", is-portrait);
            return returnValue;
        }
        opacity: self.on-is-portrait-changed(root.is-portrait, 1);
    }

and this debug log is also visible for every window resize.