1. First of all, For this tricks your device should be Rooted – Click for Rooting Guide.
2. Then Download & Install Xposed Installer in your Android Device – Click here to Download.
3. Then after Download & Install XmultiWindow in your Android Device – Click here to Download.
4. Then Click on “Framework” then Click on Install/Update and Allow Root Access to Xposed Installer.
5. It will Ask you to Reboot your Device but Click on Cancel.
6. Then Choose “Modules” From the menu on Xposed Installer.
7. Then select XmultiWindows.
8. Then Reboot your Device.
9. Once your Device is Rebooted, Open XmultiWindows.
10. Then, Download & Install MultiWindowsSidebar in your Android Device – Click here to Download.
10. Then Click on “Select Apps” and and click on “ADD ” Select all of your Apps that you want to use in multi window.
11. Then Click on “Drag Launch Mode” and select “XMultiWindow”.