Here are some tips to get 0.4.9 working better:
Use a physical mouse. Any that use USB dongle or USB connection are good. This is your get out of jail free card.
Try to disable “right stick mapped as mouse” for your controller in android settings.
Use App Cloner app to clone LS client apk.
Set “Lean back launcher support” and “Mark as game” flags in “Android Wear & TV options”
Clone and install cloned apk.
Opt in to Steam client beta.*
You can view change logs and more at https://steamcommunity.com/groups/SteamClientBeta#announcements
This illustrates that there currently are many steam client mouse related issues being worked on.
Set up controller through Steam client.
The software integrated into steam client for handling controllers is called Steam Input and it will make literally any controller work like expected with many additional benefits. Uber slick and highly configurable.
Launch all games through steam client, even if you have to use “add non-steam game” options to do this.