How do I activate a script only if the mouse is at a certain coordinate of the screen without interfering with my keyboard? - autohotkey

Question

I cooked up a script that lets me map my keyboard's media shortcuts to my mouse LRM buttons when they are pressed while the mouse coordinate is leftmost or rightmost of the screen. While it does work, I'm having having strange side effects:
When I have caps lock on, ever few strokes the letter comes out lowercase.
When I use shift to type capital letters for an extended period of time, this will turn on caps lock
Using the keyboard history, I see that my script is constantly sending the "Alt Up" key, I did this so that it release the "Alt Down" state, but something is off.
My goal is to send an modifier key when a mouse is over a certain coordinate, so that when I click with that mouse button, it launches another ahk-programmed shortcut. But can't figure out where the logic error is in my code or thinking process.
Here's the script:
; ------------------------
; Global Initializers
#InstallKeybdHook
#MaxThreadsPerHotkey 1
; ---------------------
; Control Spotify; position your mouse top-most edge and use L/M/R-mouse keys.
SetTimer, WatchCursorx, 1000
return
WatchCursorx:
CoordMode, Mouse, Screen
MouseGetPos, xpos, ypos
;Based on location of the mouse simulate shortcut activation
If (xpos == 2559 || xpos == 0)
{
Send {Alt Down}
}
Else
{
Send {Alt Up}
}
return
;Define shortcuts mentioned above
!RButton::
Send {Media_Next}
return
!LButton::
Send {Media_Prev}
return
!MButton::
send {Media_Play_Pause}
return

Answer 1

#If(docs) is meant for this.
You could use it for example like this:
CoordMode, Mouse, Screen
#If, MouseOnTheRight()
LButton::SendInput, {Media_Prev}
RButton::SendInput, {Media_Next}
MButton::SendInput, {Media_Play_Pause}
#If
MouseOnTheRight()
{
MouseGetPos, x
return x == A_ScreenWidth - 1
}

Answer 2

Per my comments, try it like this:
CoordMode, Mouse, Screen
~RButton::
MouseGetPos, xpos, ypos
If (xpos == 2559 || xpos == 0)
{
Send {Media_Next}
sleep, 500
Send {esc} ' this gets rid of right context menu
}
return
~LButton::
MouseGetPos, xpos, ypos
If (xpos == 2559 || xpos == 0)
Send {Media_Prev}
return
~MButton::
MouseGetPos, xpos, ypos
If (xpos == 2559 || xpos == 0)
Send {Media_Play_Pause}
return
Note, the preceding ~ lets the original mouse click go through so ordinarily the context menu will come up on right click. I add a Sleep and Send Escape key to dismiss . . . Ymmv