RichMinichiello's post in On Screen Keyboard was marked as the answer
Alright, here it is! I think this is pretty good! Let me know if you think it needs anything else:
#include <GUIConstantsEx.au3>
#include <WindowsConstants.au3>
#include <WinAPI.au3>
#include <ButtonConstants.au3>
;$WS_EX_NOACTIVATE = 0x08000000
$MA_NOACTIVATE = 3
$MA_NOACTIVATEANDEAT = 4
; Create "keyboard" GUI
$hGUI = GUICreate("On Screen Keyboard - v. 14.3.17", 587, 203, 564, 614, -1, BitOR($WS_EX_TOOLWINDOW, $WS_EX_TOPMOST, $WS_EX_NOACTIVATE))
$dummy1 = GUICtrlCreateDummy()
$tilda = GUICtrlCreateButton("`", 0, 0, 42, 41)
$1 = GUICtrlCreateButton("1", 40, 0, 43, 41)
$2 = GUICtrlCreateButton("2", 80, 0, 43, 41)
$3 = GUICtrlCreateButton("3", 120, 0, 43, 41)
$4 = GUICtrlCreateButton("4", 160, 0, 43, 41)
$5 = GUICtrlCreateButton("5", 200, 0, 43, 41)
$6 = GUICtrlCreateButton("6", 240, 0, 43, 41)
$7 = GUICtrlCreateButton("7", 280, 0, 43, 41)
$8 = GUICtrlCreateButton("8", 320, 0, 43, 41)
$9 = GUICtrlCreateButton("9", 360, 0, 43, 41)
$0 = GUICtrlCreateButton("0", 400, 0, 43, 41)
$dash = GUICtrlCreateButton("-", 440, 0, 43, 41)
$eq = GUICtrlCreateButton("=", 480, 0, 43, 41)
$bs = GUICtrlCreateButton("Backspace", 522, 0, 59, 41)
GUICtrlCreateButton("Tab", 0, 40, 59, 41)
$q = GUICtrlCreateButton("q", 58, 40, 43, 41)
$w = GUICtrlCreateButton("w", 98, 40, 43, 41)
$e = GUICtrlCreateButton("e", 138, 40, 43, 41)
$r = GUICtrlCreateButton("r", 178, 40, 43, 41)
$t = GUICtrlCreateButton("t", 218, 40, 43, 41)
$y = GUICtrlCreateButton("y", 258, 40, 43, 41)
$u = GUICtrlCreateButton("u", 298, 40, 43, 41)
$i = GUICtrlCreateButton("i", 338, 40, 43, 41)
$o = GUICtrlCreateButton("o", 378, 40, 43, 41)
$p = GUICtrlCreateButton("p", 418, 40, 43, 41)
$OpenBracket = GUICtrlCreateButton("[", 458, 40, 43, 41)
$CloseBracket = GUICtrlCreateButton("]", 498, 40, 43, 41)
$BkSlash = GUICtrlCreateButton("\", 538, 40, 43, 41)
GUICtrlCreateButton("", 0, 80, 75, 41)
$a = GUICtrlCreateButton("a", 73, 80, 43, 41)
$s = GUICtrlCreateButton("s", 113, 80, 43, 41)
$d = GUICtrlCreateButton("d", 153, 80, 43, 41)
$f = GUICtrlCreateButton("f", 193, 80, 43, 41)
$g = GUICtrlCreateButton("g", 233, 80, 43, 41)
$h = GUICtrlCreateButton("h", 273, 80, 43, 41)
$j = GUICtrlCreateButton("j", 312, 80, 43, 41)
$k = GUICtrlCreateButton("k", 353, 80, 43, 41)
$l = GUICtrlCreateButton("l", 393, 80, 43, 41)
$semicolon = GUICtrlCreateButton(";", 433, 80, 43, 41)
$quotes = GUICtrlCreateButton("'", 473, 80, 43, 41)
GUICtrlCreateButton("Enter", 514, 80, 67, 41)
GUICtrlCreateButton("Shift", 0, 120, 91, 41)
$z = GUICtrlCreateButton("z", 89, 120, 43, 41)
$x = GUICtrlCreateButton("x", 129, 120, 43, 41)
$c = GUICtrlCreateButton("c", 169, 120, 43, 41)
$v = GUICtrlCreateButton("v", 209, 120, 43, 41)
$b = GUICtrlCreateButton("b", 249, 120, 43, 41)
$n = GUICtrlCreateButton("n", 289, 120, 43, 41)
$m = GUICtrlCreateButton("m", 329, 120, 43, 41)
$comma = GUICtrlCreateButton(",", 369, 120, 43, 41)
$Period = GUICtrlCreateButton(".", 409, 120, 43, 41)
$FrontSlash = GUICtrlCreateButton("/", 449, 120, 43, 41)
GUICtrlCreateButton("", 490, 120, 91, 41)
GUICtrlCreateButton("", 0, 160, 59, 41)
GUICtrlCreateButton("L-Win", 56, 160, 59, 41, $BS_ICON)
GUICtrlSetImage(-1, "C:\Windows\windows_flag.ico", -1)
GUICtrlCreateButton("Alt", 112, 160, 59, 41)
GUICtrlCreateButton("Space", 168, 160, 187, 41)
GUICtrlCreateButton("Alt", 352, 160, 59, 41)
GUICtrlCreateButton("R-Win", 409, 160, 58, 41, $BS_ICON)
GUICtrlSetImage(-1, "C:\Windows\windows_flag.ico", -1)
GUICtrlCreateButton("", 465, 160, 51, 41)
GUICtrlCreateButton("Close", 515, 160, 66, 41)
$dummy2 = GUICtrlCreateDummy()
GUISetState()
GUIRegisterMsg($WM_MOUSEACTIVATE, 'WM_EVENTS')
;KN71Run("notepad.exe")
$Shift = 0
While 1
$msg = GUIGetMsg()
Switch $msg
Case $GUI_EVENT_CLOSE
send ("{SHIFTUP}")
Exit
Case $dummy1 To $dummy2
Local $sText = ControlGetText($hGUI, "", $msg)
; Write key
If $sText = "Space" Then
Send("{SPACE}")
ElseIf $sText = "Enter" Then
Send("{ENTER}")
ElseIf $sText = "L-Win" Then
Send("{LWIN}")
ElseIf $sText = "R-Win" Then
Send("{RWIN}")
ElseIf $sText = "Tab" Then
Send("{TAB}")
ElseIf $sText = "Backspace" Then
send("{BS}")
ElseIf $sText = "Shift" Then
If $Shift = 0 Then
GUICtrlSetData($tilda,"~")
GUICtrlSetData($1,"!")
GUICtrlSetData($2,"@")
GUICtrlSetData($3,"#")
GUICtrlSetData($4,"$")
GUICtrlSetData($5,"%")
GUICtrlSetData($6,"^")
GUICtrlSetData($7,'&&')
GUICtrlSetData($8,"*")
GUICtrlSetData($9,"(")
GUICtrlSetData($0,")")
GUICtrlSetData($dash,"_")
GUICtrlSetData($eq,"+")
GUICtrlSetData($q,"Q")
GUICtrlSetData($w,"W")
GUICtrlSetData($e,"E")
GUICtrlSetData($r,"R")
GUICtrlSetData($t,"T")
GUICtrlSetData($y,"Y")
GUICtrlSetData($u,"U")
GUICtrlSetData($i,"I")
GUICtrlSetData($o,"O")
GUICtrlSetData($p,"P")
GUICtrlSetData($OpenBracket,"{")
GUICtrlSetData($CloseBracket,"}")
GUICtrlSetData($BkSlash,"|")
GUICtrlSetData($a,"A")
GUICtrlSetData($s,"S")
GUICtrlSetData($d,"D")
GUICtrlSetData($f,"F")
GUICtrlSetData($g,"G")
GUICtrlSetData($h,"H")
GUICtrlSetData($j,"J")
GUICtrlSetData($k,"K")
GUICtrlSetData($l,"L")
GUICtrlSetData($semicolon,":")
GUICtrlSetData($quotes,'"')
GUICtrlSetData($z,"Z")
GUICtrlSetData($x,"X")
GUICtrlSetData($c,"C")
GUICtrlSetData($v,"V")
GUICtrlSetData($b,"B")
GUICtrlSetData($n,"N")
GUICtrlSetData($m,"M")
GUICtrlSetData($comma,"<")
GUICtrlSetData($Period,">")
GUICtrlSetData($FrontSlash,"?")
;~ Send("{SHIFTDOWN}")
$Shift = 1
Else
GUICtrlSetData($tilda,"`")
GUICtrlSetData($1,"1")
GUICtrlSetData($2,"2")
GUICtrlSetData($3,"3")
GUICtrlSetData($4,"4")
GUICtrlSetData($5,"5")
GUICtrlSetData($6,"6")
GUICtrlSetData($7,"7")
GUICtrlSetData($8,"8")
GUICtrlSetData($9,"9")
GUICtrlSetData($0,"0")
GUICtrlSetData($dash,"-")
GUICtrlSetData($eq,"=")
GUICtrlSetData($q,"q")
GUICtrlSetData($w,"w")
GUICtrlSetData($e,"e")
GUICtrlSetData($r,"r")
GUICtrlSetData($t,"t")
GUICtrlSetData($y,"y")
GUICtrlSetData($u,"u")
GUICtrlSetData($i,"i")
GUICtrlSetData($o,"o")
GUICtrlSetData($p,"p")
GUICtrlSetData($OpenBracket,"[")
GUICtrlSetData($CloseBracket,"]")
GUICtrlSetData($BkSlash,"\")
GUICtrlSetData($a,"a")
GUICtrlSetData($s,"s")
GUICtrlSetData($d,"d")
GUICtrlSetData($f,"f")
GUICtrlSetData($g,"g")
GUICtrlSetData($h,"h")
GUICtrlSetData($j,"j")
GUICtrlSetData($k,"k")
GUICtrlSetData($l,"l")
GUICtrlSetData($semicolon,";")
GUICtrlSetData($quotes,"'")
GUICtrlSetData($z,"z")
GUICtrlSetData($x,"x")
GUICtrlSetData($c,"c")
GUICtrlSetData($v,"v")
GUICtrlSetData($b,"b")
GUICtrlSetData($n,"n")
GUICtrlSetData($m,"m")
GUICtrlSetData($comma,",")
GUICtrlSetData($Period,".")
GUICtrlSetData($FrontSlash,"/")
$Shift = 0
EndIf
ElseIf $sText = "Close" Then
;send ("{SHIFTUP}")
Exit
Else
if $sText = '&&' Then
send('&')
Else
Send($sText,1)
EndIf
EndIf
EndSwitch
WEnd
Func WM_EVENTS($hWndGUI, $MsgID, $WParam, $LParam)
Switch $hWndGUI
Case $hGUI
Switch $MsgID
Case $WM_MOUSEACTIVATE
; Check mouse position
Local $aMouse_Pos = GUIGetCursorInfo($hGUI)
If $aMouse_Pos[4] <> 0 Then
Local $word = _WinAPI_MakeLong($aMouse_Pos[4], $BN_CLICKED)
_SendMessage($hGUI, $WM_COMMAND, $word, GUICtrlGetHandle($aMouse_Pos[4]))
EndIf
Return $MA_NOACTIVATEANDEAT
EndSwitch
EndSwitch
Return $GUI_RUNDEFMSG
EndFunc
