This Xposed module adds a floating action menu button to the recent apps screen from which you can launch floating apps.
Current floating apps • Calculator • Camera • Widget - Launch a widget from any app in a floating window • Browser • Note - Write and save notes • Todo List
How it works When you launch the app, you can click the plus button in the bottom right corner to add a menu item. You can add any of the above items. The free version is limited to three menu items. With the pro version you can add as many as you want. After you have added a few menu items, you have to either restart your phone or click the settings cog and click restart SystemUI (requires root). You can also find a couple of other settings here. If you launch your recent apps screen now, you should see a floating menu button from which you can launch the floating apps. You can move the floating app by holding and dragging the top bar and resize them by holding and dragging the bottom right corner.
You can also use this app without Xposed by just launching the app and clicking an item in the list. This will also launch the floating app. You won't have the floating menu button in the recent apps screen though.