B4A Library Dyna Key, customs keyboards library.

'Definitions
    Dim FuncKeyb  As DynaKey      ' define a keyboard class
    Dim font1,font2,font3,font4 As Float   ' define fonts predefined.
    Dim ufont1,ufont2,ufont3 As Float

' init, and 5x5 array of keys ,parents and size, (see full code)
    NumKeyb.Initialize(parentname,act,pan1,00%x,50%y,100%x,50%y,5,5)   'parent,x,y,w,h,col,rows (all boxes botons)

' defining a font make more visual "homogeneus?" and easy to change.
' Test in others phones size. ( work for me)
    font1=NumKeyb.SETFONTsize("8",Typeface.DEFAULT,58,1,1)
    font2=NumKeyb.SETFONTsize("MR",Typeface.DEFAULT,58,1,1)
    ..........................................

' define any key in  x,y array position  , in this case 5x5
'+ cell size (if ocupies more that one , like spacerbar horizontal or vertical
' name, font and color
' uppername , font and color
' gradient colors background
' tag that is send back to you by dynakey class.
        NumKeyb.addbutton(0,0,1,1,"(",font3,Colors.white,"",ufont1,Colors.blue,Colors.darkgray,Colors.black,"(")
        NumKeyb.addbutton(1,0,1,1,")",font3,Colors.white,"",ufont1,Colors.black,Colors.DarkGray,Colors.black,")")
        NumKeyb.addbutton(2,0,1,1,"<<",font3,Colors.white,"",ufont1,Colors.red,Colors.DarkGray,Colors.black,"<<")
     
...........................................................................................

Sub DynaKey_Click(b As Button)
    vib.Vibrate(30)
    ToastMessageShow(b.tag,False)
    Select b.tag
        Case "@"  ' The idea is that arroba (or you prefer) , use the keyname of the boton.
                 ' If you press A, read A from b.text
                 ' Both click and long click send a tag and a the principal name.
                 ' We must supose a long click are relation of the litle upper name.
            Log("   "&b.Text)

        Case "U"
            ToastMessageShow("DevMode",True)
        Case "F"
            ToastMessageShow("AppMode",True)
        Case "K"
            ToastMessageShow("FixMode",True)
        Case "<"
        Case ">"
        Case "ABC"
            setpanels (True,False,False)
        Case "123","_"
            setpanels (False,False,True)
        Case "FUN"
            setpanels (True,False,False)
        Case ">>"
        Case "<<"    
        Case "0","1","2","3","4","5","6","7","8","9","*","."
        Case "MR"
        Case "M+"
        Case "M-"
        Case "CPI","COS(","SIN(","TAN(","LOG(","POWER","RAIZ","ABS","MOD","(",")","/","%"
        Case "*","/","+","-"
        Case "="
        Case Else
            ToastMessageShow(b.tag,False)
    End Select

End Sub