Add PopupDialog widget - draggable, re-focusable dialog.

[mtwebster]

• baseDialog.js: adds a base class for shared code between modal
  and popup dialog.
• popupDialog.js: Draggable wrapper for Dialog.Dialog, to use in
  place of ModalDialog.
• The 'popup-dialog' css class can be used to help differeniation.
  In the default theme, there's a faint box shadow that uses the
  accent color.

ref:
https://github.com/orgs/linuxmint/discussions/774

[github-actions]

Best-practices scanner

This is a regex-based check for API usage that can pose security, performance or
maintainability issues, or that may already be provided by Cinnamon. Having code flagged
by it doesn't automatically disqualify a pull request.

This check is not perfect will not replace a normal review.

---

Found 3 potential issue(s):

⚠️ global_begin_modal

js/ui/popupDialog.js:168

this._dragGrabbed = global.begin_modal(global.get_current_time(), 0);

global.begin_modal() grabs all keyboard and mouse input exclusively.
Improper use will freeze the desktop. This should never be used in third-party code.

⚠️ global_set_stage_input_mode

js/ui/popupDialog.js:82

global.set_stage_input_mode(Cinnamon.StageInputMode.NORMAL);

global.set_stage_input_mode() controls how all input events are routed.
Misuse can make the desktop unresponsive. This should never be used in third-party code.

js/ui/popupDialog.js:103

global.set_stage_input_mode(Cinnamon.StageInputMode.FOCUSED);

global.set_stage_input_mode() controls how all input events are routed.
Misuse can make the desktop unresponsive. This should never be used in third-party code.

---

Automated pattern check.

[github-actions]

Best-practices scanner

This is a regex-based check for API usage that can pose security, performance or
maintainability issues, or that may already be provided by Cinnamon. Having code flagged
by it doesn't automatically disqualify a pull request.

This check is not perfect will not replace a normal review.

---

Found 3 potential issue(s):

⚠️ global_begin_modal

js/ui/popupDialog.js:200

this._dragGrabbed = global.begin_modal(global.get_current_time(), 0);

global.begin_modal() grabs all keyboard and mouse input exclusively.
Improper use will freeze the desktop. This should never be used in third-party code.

⚠️ global_set_stage_input_mode

js/ui/popupDialog.js:98

global.set_stage_input_mode(Cinnamon.StageInputMode.NORMAL);

global.set_stage_input_mode() controls how all input events are routed.
Misuse can make the desktop unresponsive. This should never be used in third-party code.

js/ui/popupDialog.js:119

global.set_stage_input_mode(Cinnamon.StageInputMode.FOCUSED);

global.set_stage_input_mode() controls how all input events are routed.
Misuse can make the desktop unresponsive. This should never be used in third-party code.

---

Automated pattern check.