This app allows you to connect your device to your computer and use the app as a touchpad.
Details on HippoRemote LTE ~ Wireless Keyboard, Mouse, Remote Control & GamepadSplashtop Touchpad
iOS, Alternative MiceThis app allows your device to connect to a computer and then act the touch pad for that computer.
Details on Splashtop TouchpadTouchPad
iOS, Alternative MiceThis app turns your iPhone, iTouch, or iPad into the touchpad for a computer. It has many features that aim at making navigating and using the touchpad easier. It also has select buttons for playing media such.
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