Conditionally Show/Hide Columns & Change Button Caption

After scouring the entire OzGrid, I have found the following two macros that partly satisfy what I want to achieve. BTW, following two macros are executed on Sheet2 and I want to achieve the following:
On Worksheet_Activate, show columns that match the criteria value in Sheet1.D4 (Sheet1.D4 contains a dropdown list with about 6 text values). In addition to that, if Sheet1.D4 value is blank then show all columns. Right now, it successfully shows columns that match the D4 value but does not work if that D4 value is left blank, instead it hides all columns in range (C:CV). So in short, to the first macro, I need to add the criteria if D4 is blank, then keep the sheet intact and don’t hide anything, just show all columns.Once on that sheet after the Worksheet_Activate event has occurred, with the second macro “ToggleColumnsVisibility” following things need to happen. BTW, currently this macro is assigned to a button (from Forms Toolbar).If cell D4 has a value, then the button’s caption should read “Show All” and when that button is pressed, it should show all columns in the range (C:CV), and the button's caption needs to change to “Show Selected”. In “Show Selected” mode, when that button is pressed, it needs to show all the columns that match the D4 value.If cell D4 is left blank, then the button's caption should read "No Action" and when the button is pressed, it should not do anything but just show all columns.

As you will notice in the header, my experience with Excel is very limited, so detailed instructions will be greatly appreciated. I am also hoping that proposed solution uses some of the efficient/effective ways of using loops such as described below (example taken from this website from this link http://www.ozgrid.com/VBA/SpeedingUpVBACode.htm)



Sub TrueOrFalseFaster()
Dim bYesNo As Boolean
Dim i As Integer
bYesNo = (i = 5)
MsgBox bYesNo
End Sub

Sub ToggleTrueOrFalseFaster()
Dim bYesNo As Boolean
bYesNo = Not bYesNo
MsgBox bYesNo
End Sub .........