Repository: vscode
Issue: Shift+Tab keybinding does not work in quick pick
Labels: bug,quick-pick

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- VS Code Version: 1.78.0-insider
- OS Version: Darwin x64 22.4.0

Steps to Reproduce:
I've added keybindings to enable moving forward and backwards through quick open suggestions (similar to how search suggestions work in Firefox). However while the "tab" keybinding works as expected, when I activate the "shift+tab" keybinding it deselects the currently selected item in the quick pick and does nothing else. Note that I've disabled all other bindings for the same key combination. Also it's worth pointing out that these keybindings don't interfere with accessibility as I still have full keyboard access via "option+tab" and "shift+option+tab".

keybindings.json:
```
[
    {
        "key": "tab",
        "command": "workbench.action.quickOpenSelectNext",
        "when": "inQuickOpen"
      },
      {
        "key": "shift+tab",
        "command": "workbench.action.quickOpenSelectPrevious",
        "when": "inQuickOpen"
    },
    {
        "key": "shift+tab",
        "command": "-workbench.action.terminal.focusAccessibleBuffer",
        "when": "accessibilityModeEnabled && terminalHasBeenCreated && terminalTabFocusMode && !terminalAccessibleBufferFocus || accessibilityModeEnabled && terminalProcessSupported && terminalTabFocusMode && !terminalAccessibleBufferFocus"
    },
    {
        "key": "shift+tab",
        "command": "-acceptAlternativeSelectedSuggestion",
        "when": "suggestWidgetHasFocusedSuggestion && suggestWidgetVisible && textInputFocus"
    },
    {
        "key": "shift+tab",
        "command": "-insertPrevSuggestion",
        "when": "hasOtherSuggestions && textInputFocus && !inSnippetMode && !suggestWidgetVisible && config.editor.tabCompletion == 'on'"
    },
    {
        "key": "shift+tab",
        "command": "-jumpToPrevSnippetPlaceholder",
        "when": "editorTextFocus && hasPrevTabstop && inSnippetMode"
    },
    {
        "key": "shift+tab",
        "command": "-outdent",
        "when": "editorTextFocus && !editorReadonly && !editorTabMovesFocus"
    },
    {
        "key": "shift+tab",
        "command": "workbench.action.closeWindow",
        "when": "!editorIsOpen && !multipleEditorGroups"
    }
]
```

keyboard shortcuts troubleshooting logs:
```
2023-04-25 13:45:11.026 [info] [KeybindingService]: / Received  keydown event - modifiers: [], code: Tab, keyCode: 9, key: Tab
2023-04-25 13:45:11.055 [info] [KeybindingService]: | Converted keydown event - modifiers: [], code: Tab, keyCode: 2 ('Tab')
2023-04-25 13:45:11.056 [info] [KeybindingService]: | Resolving [Tab]
2023-04-25 13:45:11.056 [info] [KeybindingService]: \ From 10 keybinding entries, matched workbench.action.quickOpenSelectNext, when: inQuickOpen, source: user.
2023-04-25 13:45:11.056 [info] [KeybindingService]: + Invoking command workbench.action.quickOpenSelectNext.
2023-04-25 13:45:15.198 [info] [KeybindingService]: / Received  keydown event - modifiers: [shift], code: ShiftLeft, keyCode: 16, key: Shift
2023-04-25 13:45:15.198 [info] [KeybindingService]: | Converted keydown event - modifiers: [shift], code: ShiftLeft, keyCode: 4 ('Shift')
2023-04-25 13:45:15.198 [info] [KeybindingService]: \ Keyboard event cannot be dispatched in keydown phase.
2023-04-25 13:45:27.314 [info] [KeybindingService]: + Ignoring single modifier shift due to it being pressed together with other keys.
```