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List: Reset selection state when length decreases #5875

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List: Reset selection state when length decreases #5875

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15 changes: 15 additions & 0 deletions widget/list.go
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Original file line number Diff line number Diff line change
Expand Up @@ -703,6 +703,21 @@ func (l *listLayout) updateList(newOnly bool) {
fyne.LogError("Missing UpdateCell callback required for List", nil)
}

if l.list.currentFocus >= length {
l.list.focused = false
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@andydotxyz andydotxyz Aug 3, 2025

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

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@redawl redawl Aug 3, 2025

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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.

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@andydotxyz andydotxyz Aug 3, 2025

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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...

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@redawl redawl Aug 3, 2025

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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()
}

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@andydotxyz andydotxyz Aug 3, 2025

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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...

}

if l.list.selected != nil {
index := 0
for _, selected := range l.list.selected {
if selected < length {
l.list.selected[index] = selected
index++
}
}
l.list.selected = l.list.selected[:index]
}

// l.wasVisible now represents the currently visible items, while
// l.visible will be updated to represent what is visible *after* the update
l.wasVisible = append(l.wasVisible, l.visible...)
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29 changes: 29 additions & 0 deletions widget/list_internal_test.go
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Original file line number Diff line number Diff line change
Expand Up @@ -685,6 +685,35 @@ func TestList_ScrollToLargeItem(t *testing.T) {
assert.Equal(t, list.scroller.Content.MinSize().Height-list.Size().Height, list.scroller.Offset.Y)
}

func TestList_SelectionReset(t *testing.T) {
data := []string{
"Test1",
"Test2",
"Test3",
}
list := NewList(
func() int { return len(data) },
func() fyne.CanvasObject { return NewLabel("Templ") },
func(id ListItemID, item fyne.CanvasObject) { item.(*Label).SetText(data[id]) },
)

list.Select(2)
list.Refresh()

assert.Equal(t, len(list.selected), 1)

data = make([]string, 0)
list.Refresh()
assert.Equal(t, len(list.selected), 0)

data = []string{
"Test1",
"Test2",
}
list.Refresh()
assert.Equal(t, len(list.selected), 0)
}

var minSize fyne.Size

func BenchmarkContentMinSize(b *testing.B) {
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