Support Ctrl+[backspace/delete] to delete the word to the left or right of the cursor

[dweymouth]

Adds Ctrl+Backspace and Ctrl+Delete shortcuts to Entry for deleting the word to the left and right of the cursor, respectively. On Mac OS, the modifier is option (aka alt) instead.

Fixes #4524

Checklist:

• Tests included.
• Lint and formatter run with no errors.
• Tests all pass.

[coveralls]

coverage: 64.797% (+0.04%) from 64.756%
when pulling da4d56c on dweymouth:ctrl-backspace
into 3c111a2 on fyne-io:develop.

[Jacalz]

Nice work. A much better implementation than what I had. However, I managed to get it to crash in two ways.

1. Write a single space into the entry and move the cursor to the left.
2. Clicking CTRL + BACKSPACE or CTRL + DELETE will now crash.

panic: runtime error: makeslice: len out of range

goroutine 66 [running]:
fyne.io/fyne/v2/widget.(*RichText).deleteFromTo(0xc00292d800, 0x14, 0x13)
	/var/home/jacob/git/fyne/widget/richtext.go:184 +0x2cf
fyne.io/fyne/v2/widget.(*Entry).deleteWord(0xc003ceb400, 0x1)
	/var/home/jacob/git/fyne/widget/entry.go:907 +0xe5
fyne.io/fyne/v2/widget.(*Entry).registerShortcut.func12({0xc003ceb450, 0xbe0d60})
	/var/home/jacob/git/fyne/widget/entry.go:1214 +0x1c
fyne.io/fyne/v2.(*ShortcutHandler).TypedShortcut(0xc003ceb450, {0xe4c340, 0xc0035ae060})
	/var/home/jacob/git/fyne/shortcut.go:21 +0x6e
fyne.io/fyne/v2/widget.(*Entry).TypedShortcut(0xc00010e360?, {0xe4c340?, 0xc0035ae060?})
	/var/home/jacob/git/fyne/widget/entry.go:963 +0x25
fyne.io/fyne/v2/internal/driver/glfw.(*window).triggersShortcut.func1()
	/var/home/jacob/git/fyne/internal/driver/glfw/window.go:907 +0x24
fyne.io/fyne/v2/internal/driver/common.(*Window).RunEventQueue(0x0?)
	/var/home/jacob/git/fyne/internal/driver/common/window.go:35 +0x38
created by fyne.io/fyne/v2/internal/driver/glfw.(*gLDriver).createWindow.func1 in goroutine 1
	/var/home/jacob/git/fyne/internal/driver/glfw/window.go:961 +0x145

[dweymouth]

Hmm, I'm getting a different crash:

panic: runtime error: slice bounds out of range [-1:]

goroutine 11 [running]:
fyne.io/fyne/v2/widget.getTextWhitespaceRegion({0x1400150ff30?, 0x1?, 0x140000d0270?}, 0x14001261ef0?, 0x1)
	/Users/drew/fyne/widget/entry.go:2181 +0x17c
fyne.io/fyne/v2/widget.(*Entry).deleteWord(0x140001e8000, 0x1)
	/Users/drew/fyne/widget/entry.go:890 +0x50
fyne.io/fyne/v2/widget.(*Entry).registerShortcut.func12({0x140001e8050, 0x102a38e20})
	/Users/drew/fyne/widget/entry.go:1214 +0x24
fyne.io/fyne/v2.(*ShortcutHandler).TypedShortcut(0x140001e8050, {0x102b21258, 0x14001c84fc0})
	/Users/drew/fyne/shortcut.go:21 +0x78
fyne.io/fyne/v2/widget.(*Entry).TypedShortcut(0x14000100120?, {0x102b21258?, 0x14001c84fc0?})
	/Users/drew/fyne/widget/entry.go:963 +0x2c
fyne.io/fyne/v2/internal/driver/glfw.(*window).triggersShortcut.func1()
	/Users/drew/fyne/internal/driver/glfw/window.go:907 +0x30
fyne.io/fyne/v2/internal/driver/common.(*Window).RunEventQueue(0x0?)
	/Users/drew/fyne/internal/driver/common/window.go:35 +0x3c
created by fyne.io/fyne/v2/internal/driver/glfw.(*gLDriver).createWindow.func1 in goroutine 1
	/Users/drew/fyne/internal/driver/glfw/window.go:961 +0x150

will try to dig deeper when I have some time

[Jacalz]

@dweymouth Did you manage to have another look at it? :)

[dweymouth]

@dweymouth Did you manage to have another look at it? :)

No I have not. If you happen to find the problem feel free to add a code suggestion :)