What can you do If want to Switch Quickly to another app?!
You should Leave Current app and then find & Select Another app
But by using this Application you can create *Floating Shortcuts* of your Favorites Apps to Open them Quickly.

OK Google! Open Floating Shortcuts
When you open App using OK Google! voice command.
App Will Recover All your Last Used Shortcuts

You can Create up to 10 Shortcuts / 3 Widgets & Simply Move them Around Screen.
>> If you want to Replace a shortcut by another shortcut First Remove it and then select another App from List to Create its Floating Shortcut.

Features
+ Apps for Time
Shortcut of selected App will create at specific time everyday until user cancel it.
For Example;
You Set to Create Floating Shortcut of 'Messaging App' at 10:30.
+ Apps for WiFi
+ Apps for Bluetooth
+ Apps for GPS
You can select Necessary Apps from the List then this App will create Floating Shortcuts of selected Apps When turning on the WiFi, Bluetooth & GPS
+ Auto Remove
It will remove shortcuts that created by Automation Features.
+ Floating Widgets

Preferences
+ App Drawer Style
+ App Info Text Color
+ Shortcut Size
+ Auto Transparent

Tip: To Remove Shortcut Long-Press on Icon.
Tip: To ReCreate Last Shortcuts Press Recover Option.
Tip: To Remove Widget Long-Press on Widget Name.
Tip: Long-Press on Launch Button to Resize Widget.

Floating Shortcuts PRO (Stable, Ad Free, Refined GUI)
https://goo.gl/8uwlZ1

/*
* Open Source Project of Floating Shortcut on XDA
* http://forum.xda-developers.com/android/apps-games/app-floating-shortcuts-t3019241
*
* Geeks Empire+
* https://plus.google.com/111005369532093965757
*
* Please Write your Opinion to Improve current Features & to Add New features
*/
/* [ SmApEx4SoPr ] Small Apps extension for Sony products */