Of Xcode, LightTable, and Sublime Text, all three of them support opening code in new windows in addition to in panes, tabs, and dividers. So their popularity i

Of Xcode, LightTable, and Sublime Text, all three of them support opening code in new windows in addition to in panes, tabs, and dividers. So their popularity is not evidence of MDIs being unnecessary. Whether their MDIs are necessary depends on how many people use multiple windows in those apps, and would dislike using other views if multiple windows were not an option.