Calling SetContent from Window OnDropped can freeze application

[codesoap]

Checklist

• I have searched the issue tracker for open issues that relate to the same problem, before opening a new one.
• This issue only relates to a single bug. I will open new issues for any other problems.

Describe the bug

I have added a SetOnDropped handler to the main window of my application. If the handler just does something trivial, like printing to stdout, everything works as expected. If, however, the handler calls SetContent on the window, the SetContent is run and then the application freezes forever.

How to reproduce

I can create the problem by running the test program and dropping a file into the application window.

Screenshots

No response

Example code

package main

import "fyne.io/fyne/v2"
import "fyne.io/fyne/v2/app"
import "fyne.io/fyne/v2/widget"

func main() {
	a := app.New()
	w := a.NewWindow("test")
	w.SetOnDropped(func(pos fyne.Position, uris []fyne.URI) {
		w.SetContent(widget.NewLabel("File dropped"))
	})
	w.ShowAndRun()
}

Fyne version

2.4.3

Go compiler version

1.22.0

Operating system and version

MX Linux, I believe version 21; it's basically Debian

Additional Information

No response

[codesoap]

While searching for existing code that uses SetOnDropped, I found this: https://github.com/metal3d/fyne-streamer/blob/8800be35603ad89a6599e6a09152a988655e828a/examples/blender-peertube/main.go#L111

It looks like someone else already found the bug and also found a workaround. This works:

package main

import "fyne.io/fyne/v2"
import "fyne.io/fyne/v2/app"
import "fyne.io/fyne/v2/widget"

func main() {
	a := app.New()
	w := a.NewWindow("test")
	w.SetOnDropped(func(pos fyne.Position, uris []fyne.URI) {
		go func() { w.SetContent(widget.NewLabel("File dropped")) }()
	})
	w.ShowAndRun()
}

[andydotxyz]

Updated title to be freeze not crash as they are quite different

[andydotxyz]

Fixed on Develop branch, but it probably missed v2.4.4 - if we do 2.4.5 before 2.5.0 then this should be in it

[codesoap]

Awesome, thanks for the lightning fast fix, @andydotxyz ! I'll try to test it with the development branch, when I find some time.

[codesoap]

I've now tested on the develop branch and don't see the problem anymore. Thanks again!

[codesoap]

Milestone v2.4.5 had been set for this issue, but the fix has not been released with v2.4.5. Was this ticket missed when preparing the release or was this a conscious choice?

[andydotxyz]

You're right this was missed somehow.
It is now picked to the release branch so that whatever release comes next it will certainly be included.
Sorry about that.

[codesoap]

No worries and thanks for the quick action ❤️