Various interface conversion panics when selecting text in a widget.Entry

[csmith]

Describe the bug:

Occasionally when selecting text in a multi-line widget.Entry, one of these panics occur:

panic: interface conversion: fyne.CanvasObject is *widget.textProvider, not *canvas.Rectangle

goroutine 12 [running]:
fyne.io/fyne/v2/widget.(*entryContentRenderer).Refresh(0xc000067260)
        .../go/pkg/mod/fyne.io/fyne/v2@v2.0.0/widget/entry.go:1333 +0x493
fyne.io/fyne/v2/widget.(*entryRenderer).Refresh(0xc000024680)
        .../go/pkg/mod/fyne.io/fyne/v2@v2.0.0/widget/entry.go:1193 +0x35c
fyne.io/fyne/v2/widget.(*BaseWidget).Refresh(0xc0002be480)
        .../go/pkg/mod/fyne.io/fyne/v2@v2.0.0/widget/widget.go:139 +0x5c
fyne.io/fyne/v2/widget.(*BaseWidget).setFieldsAndRefresh(0xc0002be480, 0xc00004cef0)
        .../go/pkg/mod/fyne.io/fyne/v2@v2.0.0/widget/widget.go:165 +0x7e
fyne.io/fyne/v2/widget.(*Entry).updateMousePointer(0xc0002be480, 0xc000209340, 0xc000546400)
        .../go/pkg/mod/fyne.io/fyne/v2@v2.0.0/widget/entry.go:1036 +0x97
fyne.io/fyne/v2/widget.(*Entry).Dragged(0xc0002be480, 0xc000209340)
        .../go/pkg/mod/fyne.io/fyne/v2@v2.0.0/widget/entry.go:245 +0x45
fyne.io/fyne/v2/widget.(*entryContent).Dragged(0xc0000704b0, 0xc000209340)
        .../go/pkg/mod/fyne.io/fyne/v2@v2.0.0/widget/entry.go:1253 +0x39
fyne.io/fyne/v2/internal/driver/glfw.(*window).mouseMoved.func4()
        .../go/pkg/mod/fyne.io/fyne/v2@v2.0.0/internal/driver/glfw/window.go:667 +0x38
fyne.io/fyne/v2/internal/driver/glfw.(*window).runEventQueue(0xc00014a1c0)
        .../go/pkg/mod/fyne.io/fyne/v2@v2.0.0/internal/driver/glfw/window.go:1242 +0x7a
created by fyne.io/fyne/v2/internal/driver/glfw.(*gLDriver).createWindow.func1
        .../go/pkg/mod/fyne.io/fyne/v2@v2.0.0/internal/driver/glfw/window.go:1266 +0x10d

and:

panic: interface conversion: fyne.CanvasObject is *widget.textProvider, not *canvas.Rectangle

goroutine 25 [running]:
fyne.io/fyne/v2/widget.(*entryContentRenderer).Refresh(0xc0000b7200)
        .../go/pkg/mod/fyne.io/fyne/v2@v2.0.0/widget/entry.go:1333 +0x493
fyne.io/fyne/v2/widget.(*entryRenderer).Refresh(0xc0000cc600)
        .../go/pkg/mod/fyne.io/fyne/v2@v2.0.0/widget/entry.go:1193 +0x35c
fyne.io/fyne/v2/widget.(*BaseWidget).Refresh(0xc000083200)
        .../go/pkg/mod/fyne.io/fyne/v2@v2.0.0/widget/widget.go:139 +0x5c
fyne.io/fyne/v2/widget.(*BaseWidget).setFieldsAndRefresh(0xc000083200, 0xc00004cef0)
        .../go/pkg/mod/fyne.io/fyne/v2@v2.0.0/widget/widget.go:165 +0x7e
fyne.io/fyne/v2/widget.(*Entry).updateMousePointer(0xc000083200, 0xc0004e0c60, 0xc000620300)
        .../go/pkg/mod/fyne.io/fyne/v2@v2.0.0/widget/entry.go:1036 +0x97
fyne.io/fyne/v2/widget.(*Entry).Dragged(0xc000083200, 0xc0004e0c60)
        .../go/pkg/mod/fyne.io/fyne/v2@v2.0.0/widget/entry.go:245 +0x45
fyne.io/fyne/v2/widget.(*entryContent).Dragged(0xc0000b8460, 0xc0004e0c60)
        .../go/pkg/mod/fyne.io/fyne/v2@v2.0.0/widget/entry.go:1253 +0x39
fyne.io/fyne/v2/internal/driver/glfw.(*window).mouseMoved.func4()
        .../go/pkg/mod/fyne.io/fyne/v2@v2.0.0/internal/driver/glfw/window.go:667 +0x38
fyne.io/fyne/v2/internal/driver/glfw.(*window).runEventQueue(0xc0000fe1c0)
        .../go/pkg/mod/fyne.io/fyne/v2@v2.0.0/internal/driver/glfw/window.go:1242 +0x7a
created by fyne.io/fyne/v2/internal/driver/glfw.(*gLDriver).createWindow.func1
        .../go/pkg/mod/fyne.io/fyne/v2@v2.0.0/internal/driver/glfw/window.go:1266 +0x10d

To Reproduce:

This is about a 90% reproduction for me:

1. Create a widget.Entry configured with Wrapping = fyne.TextWrapWord and MultiLine = true
2. Add sufficient text that the widget scrolls
3. Mouse down to start selecting the first line of text and drag the cursor down to select the rest, forcing the widget to scroll
4. After selecting down to the bottom, move the cursor back up to start deselecting some of the bottom text

After step 3 the selection seems to get a bit laggy, or ignores the cursor for a bit, and then when it starts again in step 4 fyne panics.

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"
)

var (
	input = widget.NewEntry()
	output = widget.NewEntry()
)

func main() {
	seeker := app.New()
	window := seeker.NewWindow("Seeker")
	window.Resize(fyne.Size{Width: 800, Height: 300})
	window.SetContent(container.NewGridWithColumns(2, leftColumn()))
	input.Wrapping = fyne.TextWrapWord
	input.MultiLine = true
	output.MultiLine = true
	output.Disable()

	input.SetText("Hello,\nthis\nis\na\ntest\nFoo\nbar\nbaz\nline\nline\nline")

	window.Show()
	seeker.Run()
}

func leftColumn() *fyne.Container {
	return container.NewGridWithColumns(1,
		container.NewBorder(
			widget.NewLabel("Input:"),
			nil,
			nil,
			nil,
			input,
		),
		container.NewBorder(
			widget.NewLabel("Output:"),
			nil,
			nil,
			nil,
			container.NewMax(output),
		),
	)
}

Device (please complete the following information):

• OS: Linux
• Version: Arch (up-to-date as of 2020-02-20)
• Go version: 1.15.8
• Fyne version: fyne.io/fyne/v2 v2.0.0 h1:TfsS3bNq5663BpXsoz1OfzyjcaMqqOf9usI8ZKkw4IE=

[csmith]

Sample content of selections when it panics:

But I can't see anywhere that actually adds a widget.textProvider to selections...

[fpabl0]

That's a good catch. Thanks for reporting this.

[Jacalz]

Fixed on the develop branch as of 78b4eaf.