sequential writes to preferences does not save to file

[zivoy]

Describe the bug:

Setting a string value with the Preferences API more than once in a row causes it to not write the latter ones to the file. unless a gap is introduced.

To Reproduce:

Steps to reproduce the behaviour:
here is a sample program

a := app.NewWithID("TESTING")
fmt.Println("Before setting")
fmt.Println(a.Preferences().String("a"))
fmt.Println(a.Preferences().String("b"))
a.Preferences().SetString("a", "aaaaaaaaaaaaa")
//<-time.After(100*time.Millisecond)
a.Preferences().SetString("b", "bbbbbbbbbbbbb")
fmt.Println("After")
fmt.Println(a.Preferences().String("a"))
fmt.Println(a.Preferences().String("b"))

take this program and run it twice.
you will see that on the second run only a is set while b is still nothing.
now uncomment the line in the middle and run it twice more.
now both a and b are set.

Device (please complete the following information):

• OS: Windows
• Version: 10
• Go version: 1.16.7
• Fyne version: 2.0.4

[andydotxyz]

Thanks for the report, this should be fixed in PR #2450, please do test and confirm :) @zivoy

[zivoy]

It's fixed, works without the need for adding the delay now.