[MTCB Software Development] oscyp:
MTC-Keys v. 3.2 allows you to choose different actions/apps/activiti on 1-click and double-click of the same button, but the settings file format is a little bit different. Also there is an action to be chosen that reads the settings file again without a need to reboot the HU.

Sample config file with all possibilities explained:

#one-click of a button
[click.1]
action_4=back
app_3=com.maxmpz.audioplayer
app_42=com.dailyroads.v

#double-click of a button
[click.2]
app_51=pl.aqurat.automapa
#activity_46=com.maxmpz.audioplayer/com.maxmpz.audioplayer.API_COMMAND
#activity_45=com.maxmpz.audioplayer/com.maxmpz.audioplayer.API_COMMAND

[settings]
# Time in milliseconds
doubleclick.time=500

#action_51 = apps
#Navi button assigned to the call list of the latest applications.

#	xx is the KEY CODE
#	app_xx = name of the package	- to launch an app (use Installed Package Viewer from GP to determine the names)
#	activity_xx = name of the package / class name	- to use specific action within an app
#	action_xx = action	- to perform one of the actions listed below:
#	You can cycle in a limited fashion, (only actions can be cycled, cycling apps or mixed apps and actions won't work) e.g.
#	"action_74 = home
#	action_74 = apps
#	action_74 = menu"
#	home:	Go to the home screen;
#	menu:	Call up menu;
#	back:	push back;
#	apps:	access the list of running applications;
#	screenshot:	screenshot of the screen;
#	sleep:	sleep mode, may not work on older MCU;
#	screenoff:	Turn off the screen, may not work on older MCU;
#	switch:	switch between two last applications;
#	settings:	configuration file read without restarting the State;
#	null:	do nothing.
#	intent_xx = intent	- to send a broadcast intent
#	event_xx = button code	- to remap physical buttons
#	media_xx = play / next / prev	- to control third-party player
#	keyevent_xx = button code	- to emulate standard softkey (refer to KEYCODE_ from https://developer.android.com/reference/android/view/KeyEvent.html)
#	command_xx = command shell	- to start shell-command as root
#	function_xx = function name	- to call functions from MicrontekServer without parameters. Without explanation, and list. Only for developers.

#--- KEY CODES ---
# Some buttons (eg Eject) are hardware and can not be intercepted by pressing the program.

# 2 the MODE, switch between full-time applications ( "Radio", "Music", etc.)
# 27 VOL-, Volume Down
# 19 VOL +, the volume Increase
# 4 MUTE, mute / unmute sound
# 23 configuration Call of sound modes and EQ
# 42 DVD, Launch an application "DVD"
# 43 RADIO, BAND, Run the application "Radio" (repeated pressing - range switching)
# ---
# 44 LOUD, Enable / disable LOUDNESS
# 45 PREV, Previous track, previous tuned radio station, the previous DVD chapter
# 46 the NEXT, next track, the next radio station tuned, the next DVD chapter
# 58 TUNE DOWN, rollback ago, the search for a radio frequency step downwards
# 59 TUNE UP, Preroll forward search radio frequency step upward
# 69 BLUETOOTH, Run the application "Handsfree"
# 70 HANGUP, put down the phone and end a call
# 80 PICKUP, lift the handset to answer the call
# ---
# 49 EQ, switch between equalizer presets
# 50 Disconnect app "Handsfree" (in fact does not work)
# 51 GPS, Starting the navigation application
# 72 AUX, Run the application "External power" (AV-In)
# 57 HOME, go to the home screen
# 73 DTV, Application launch, "Digital TV"
# 67 (presumably) Run the screen calibration (for resistive screens)
# 74 SETUP, Launch "Settings"
# 84 MUSIC, an application Running the "Music"
# 85 Switching between the screen brightness settings
# 3 PLAYPAUSE, Play / Pause
# 13 PLAYSTOP, Stop
# ---
# When running the radio
# 5.43 - The next range
# 88 - On / Off.. TA
# 87 - On / Off.. AF
# 77 - Auto without saving (Intro) with increasing frequency since the beginning of the range
# 62 - The next channel
# 61 - Previous channel
# 22.63 - Searching with decreasing frequency
# 24.64 - search with increasing frequency
# 29 - Switch to Channel 1
# 30 - Switch to Channel 2
# 31 - Switch on Channel 3
# 32 - Switch to Channel 4
# 33 - Switch on Channel 5
# 34 - Switch on channel 6
# 18 - On / Off.. ST (stereo)
# 21 - On / Off.. LOC
# 17 - Auto (?) - It is not clear how it works
# ---
# When the application is running "Handsfree"
# 69 - Go to the dialer
# 70 - Hang up
# 80 - Off-hook
# 3 - Play / Pause music
# 6,22,45,61 - Previous track / the beginning of a track (music)
# 14,24,46,62 - Next track (music)
# 13 - Stop (Music)
# 59 - Preroll (music)
# 58 - rollback (music)
# 38 - Press the digit 0
# 29 - Press the number 1
# 30 - Press the number 2
# 31 - Press the number 3
# 32 - Press the number 4
# 33 - Press the number 5
# 34 - Press the number 6
# 35 - Press the number 7
# 36 - Press the number 8
# 37 - Press the digit 9