Merge pull request #1670 from adrianre12/#1668-TabContainer-Panic-whe…

…n-removing-tabs

#1668 tab container panic when removing tabs

.gitignore

@@ -3,6 +3,10 @@ cmd/fyne/fyne
 cmd/fyne_demo/fyne_demo
 cmd/fyne_settings/fyne_settings
 cmd/hello/hello
+cmd/fyne/fyne.exe
+cmd/fyne_demo/fyne_demo.exe
+cmd/fyne_settings/fyne_settings.exe
+cmd/hello/hello.exe
 
 ### Tests
 **/testdata/failed

widget/tabcontainer.go

@@ -128,6 +128,9 @@ func (c *TabContainer) RemoveIndex(index int) {
 // SetItems sets the container’s items and refreshes.
 func (c *TabContainer) SetItems(items []*TabItem) {
 	c.Items = items
+	if l := len(c.Items); c.current >= l {
+		c.current = l - 1
+	}
 	c.Refresh()
 }
 
@@ -146,7 +149,6 @@ func (c *TabContainer) SelectTabIndex(index int) {
 	if index < 0 || index >= len(c.Items) || c.current == index {
 		return
 	}
-
 	c.current = index
 	c.Refresh()
 
@@ -360,6 +362,7 @@ func (r *tabContainerRenderer) buildTabBar(buttons []fyne.CanvasObject) *fyne.Co
 
 func (r *tabContainerRenderer) moveSelection() {
 	if r.container.current < 0 {
+		r.underline.Hide()
 		return
 	}
 	selected := r.tabBar.Objects[r.container.current]
@@ -380,6 +383,7 @@ func (r *tabContainerRenderer) moveSelection() {
 		underlinePos = fyne.NewPos(r.tabBar.Position().X-theme.Padding(), selected.Position().Y)
 		underlineSize = fyne.NewSize(theme.Padding(), selected.Size().Height)
 	}
+	r.underline.Show()
 	r.underline.Resize(underlineSize)
 	r.underline.Move(underlinePos)
 }

widget/tabcontainer_test.go

@@ -98,3 +98,16 @@ func TestTabContainer_SelectTabIndex(t *testing.T) {
 	assert.Equal(t, 1, tabs.CurrentTabIndex())
 	assert.Equal(t, tabs.Items[1], selectedTab)
 }
+
+func TestTabContainer_RemoveIndex(t *testing.T) {
+	tabs := widget.NewTabContainer(&widget.TabItem{Text: "Test1", Content: widget.NewLabel("Test1")},
+		&widget.TabItem{Text: "Test2", Content: widget.NewLabel("Test2")})
+
+	tabs.SelectTabIndex(1)
+	tabs.RemoveIndex(1)
+	assert.Equal(t, 0, tabs.CurrentTabIndex()) // check max item selection and no panic
+
+	tabs.SelectTabIndex(0)
+	tabs.RemoveIndex(0)
+	assert.Equal(t, -1, tabs.CurrentTabIndex()) // check deselection and no panic
+}