List: Reset selection state when length decreases

[redawl]

Description:

Fixes #5852

Checklist:

• Tests included.
• Lint and formatter run with no errors.
• Tests all pass.

[coveralls]

coverage: 62.404% (+0.02%) from 62.388%
when pulling 778372b on redawl:list_selection_fix
into 3ee02e8 on fyne-io:develop.

[andydotxyz]

I don't think it should look like it lost focus - the actual focus won't have changed...

[redawl]

Without this check, even though we removed the selection when the list shrunk, when the list grows again the previously selected row shows as focused, which is incorrect.

[andydotxyz]

I agree what you describe is not correct - but I'm not sure your solution is either.

If you're editing an Entry and SetText is called to shorter the cursor would move to accommodate but it would not unfocus the entry...

[redawl]

Are you saying if there is an entry inside the list row? at least with this code, the entry is properly unfocused as well:

package main

import (
        "fyne.io/fyne/v2"
        "fyne.io/fyne/v2/app"
        "fyne.io/fyne/v2/container"
        "fyne.io/fyne/v2/widget"
)

func main() {
        a := app.New()
        w := a.NewWindow("Scroll Test")
        w.Resize(fyne.NewSize(800, 800))

        items := []string{
                "Item1",
                "Item2",
                "Item3",
        }
        populateList := true
        button := widget.NewButton("Click to toggle list", func() {})

        list := widget.NewList(
                func() int {
                        if populateList {
                                return len(items)
                        }
                        return 0
                },
                func() fyne.CanvasObject {
                        return widget.NewEntry()
                },
                func(lii widget.ListItemID, co fyne.CanvasObject) {
                        co.(*widget.Entry).OnChanged = func(s string) {
                                items[lii] = s
                        }
                        co.(*widget.Entry).SetText(items[lii])
                },
        )

        button.OnTapped = func() {
                populateList = !populateList
                list.Refresh()
        }

        w.SetContent(container.NewBorder(button, nil, nil, nil, list))

        w.ShowAndRun()
}

[andydotxyz]

Are you saying if there is an entry inside the list row?

No.
I was using Entry as an illustration of the focus model. Unless the user focuses another widget the list remains focus and so we shouldn't hide the focus state...