Extending Entry widget adds space below it, when inside a Form

[matwachich]

Describe the bug:

When extending the Entry widget, there is some space

To Reproduce:

Just run the example code, and see the difference between the CustomEntry inside a Form and inside a VBox

Screenshots:

Example code:

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("TEST")

	content := container.NewGridWithColumns(2,
		widget.NewForm(
			widget.NewFormItem("Standard Entry 01", widget.NewEntry()),
			widget.NewFormItem("Custom Entry", NewCustomEntry()),
			widget.NewFormItem("Standard Entry 02", widget.NewEntry()),
		),
		container.NewVBox(
			widget.NewEntry(),
			NewCustomEntry(),
			widget.NewEntry(),
		),
	)
	content.Objects[0].(*widget.Form).OnSubmit = func() {
		println("Submit...")
	}

	w.SetContent(content)
	w.Resize(fyne.NewSize(800, 500))
	w.CenterOnScreen()
	w.ShowAndRun()
}

type CustomEntry struct {
	widget.Entry
}

func NewCustomEntry() *CustomEntry {
	ce := &CustomEntry{}
	ce.ExtendBaseWidget(ce)
	return ce
}

Device (please complete the following information):

• OS: Windows 10
• Version: 10.0.18363.2212
• Go version: 1.18.2
• Fyne version: 2.2.0

[andydotxyz]

I think this relates to the validation, perhaps the default setup is not proving a clean setup...
Thanks for opening, we should try and figure this out - though it may relate to #2964

[matwachich]

Some new information: the bug seems to exist also for a standard SelectEntry (not extended widget) inside a Form

// build & return layout
	return container.New(&PercentColsLayout{Percents: []int{30, 70}},
		container.NewBorder(tab.toolbar, tab.author, nil, nil, tab.list),
		container.NewBorder(
			&widget.Form{Items: []*widget.FormItem{
				{Text: "Titre", Widget: tab.Titre},
				{Text: "Catégorie", Widget: tab.Categorie},
				{Text: "", Widget: tab.Public},
			}},
			nil, nil, nil,

[andydotxyz]

Ah yes, this is helpful thanks

[matwachich]

Some new information: setting a non nil Validator to a standard Entry gives the same effet.
So it is definitly related to Validation. It's like something says to the layout that a custom Entry is like an Entry with a Validator.