ui.Entry event OnChanged doesn't fire for its SetText function

Hi,
for me, the ui.Entry event OnChanged doesn't fire for its SetText function. My setup is like this:

```go
myInput = ui.NewEntry()
myOpenButton.OnClicked(func(_ *ui.Button) {
file := ui.OpenFile(window)
myInput.SetText(file)
})
myInput.OnChanged(func(_ *ui.Entry) {
fmt.Println(myInput.Text())
})
```
When I enter something manually in the entry field, the event gets fired just fine. But it doesn't fire for `myInput.SetText(file)`. Of course, I can easily work around that, just noticing. :)
Currently, it looks like this:

```go
myInputOnChanged := func(_ *ui.Entry) {
fmt.Println(myInput.Text())
}
myOpenButton.OnClicked(func(_ *ui.Button) {
file := ui.OpenFile(window)
myInput.SetText(file)
myInputOnChanged(nil)
})
myInput.OnChanged(myInputOnChanged)
```