Can't resize using mouse since 2.8.0

Replace resize widgets with options in settings dialog.

Please bring back the function to resize the menu using mouse. Setting blindly width and height in pixels in settings is too hard and it's too much inconvenience to the user.

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Btw. I downgraded to 2.7.3 and lost all settings 😞

Edit: I think if new xfconf settings already exists, it shouldn't overwrite it by old RC settings if it appears after downgrade->upgrade (to not lose settings permanently).