The Back, Home and Overview buttons (left pointing triangle, circle, square) buttons don't do anything when clicked in Emulator.
Go into avd folder. You will find it in:
$ANDROID_AVD_HOMEif you have set it.$ANDROID_SDK_HOME\avd$HOME\.android\avd$LOCALAPPDATA\.android\avd
In the .avd folder for your emulator (e.g. flutter_emulator.avd), there is a file config.ini. In this file, set hw.keyboard to yes.