Fix postion of line during deletion

Fixes fyne-io#3905

container/doctabs.go

@@ -244,7 +244,12 @@ func (r *docTabsRenderer) Layout(size fyne.Size) {
 	r.updateCreateTab()
 	r.updateTabs()
 	r.layout(r.docTabs, size)
+
+	// lay out buttons before updating indicator, which is relative to their position
+	buttons := r.scroller.Content.(*fyne.Container)
+	buttons.Layout.Layout(buttons.Objects, buttons.Size())
 	r.updateIndicator(r.docTabs.transitioning())
+
 	if r.docTabs.transitioning() {
 		r.docTabs.setTransitioning(false)
 	}

container/doctabs_internal_test.go

@@ -30,3 +30,19 @@ func TestDocTabs_tabButtonRenderer_SetText(t *testing.T) {
 	renderer = cache.Renderer(button).(*tabButtonRenderer)
 	assert.Equal(t, "Replace", renderer.label.Text)
 }
+
+func TestDocTabs_tabButtonRenderer_Remove(t *testing.T) {
+	items := []*TabItem{{Text: "1", Content: widget.NewLabel("Content1")},
+		{Text: "2", Content: widget.NewLabel("Content2")},
+		{Text: "3", Content: widget.NewLabel("Content3")}}
+	tabs := NewDocTabs(items...)
+	tabs.Resize(fyne.NewSize(100, 100))
+	tabRenderer := cache.Renderer(tabs).(*docTabsRenderer)
+
+	tabs.SelectIndex(1)
+	pos := tabRenderer.indicator.Position()
+	tabs.RemoveIndex(0)
+	assert.Equal(t, 0, tabs.SelectedIndex())
+
+	assert.Less(t, tabRenderer.indicator.Position().X, pos.X)
+}