What Excel VBA actions are possible on hidden worksheets or workbooks?

Question

Hidden worksheets/workbooks have some limitations to what can be done in VBA code, like most Select and Selection statements, and anything coming from ActiveSheet, but I can't seem to find any list of what the limitations are.

Google, the built-in documentation in the help system, and MSDN's website have all failed me. Can anyone point me in the right direction?

Edit: The workbook is opened with

Set WB_Master = Workbooks.Open(Filename:=PATH_Master, ReadOnly:=False)

and then hidden with

WB_Master.Windows(1).Visible = False

Answer 1

From the Visual Basic for Applications help:

When an object is hidden, it's removed from the screen and its Visible property is set to False. A hidden object's controls aren't accessible to the user, but they are available programmatically to the running application, to other processes that may be communicating with the application through Automation, and in Windows, to Timer control events.

Not much help there I'm afraid, and I couldn't find much else through Google.

As you said yourself, the Select method and Selection Property don't work on a hidden Worksheet, they should work on a hidden Workbook though. (Please correct me if I'm wrong.) In general however, it's not always all that efficient to select ranges in worksheets anyway, you are better off working with the Range property (which does work on a hidden worksheet).

EDIT:

The following code will change the color of A1:A8 to Cyan even when the Worksheet is not visible:

Dim book2 As Workbook
Set book2 = Workbooks.Open("C:\Book2.xls")

book2.Worksheets("Sheet1").Visible = False
book2.Windows(1).Visible = False

With book2.Worksheets("Sheet1").Range("A1:E8").Interior
    .ColorIndex = 8
    .Pattern = xlSolid
    .PatternColorIndex = xlAutomatic
End With

book2.Windows(1).Visible = True
book2.Worksheets("Sheet1").Visible = True

Answer 2

You can get around any limitations on hidden sheets by unhiding them without the user realizing it, doing whatever you need to, and then hiding them again.

This example assumes that Sheet2 is hidden.

Sub DoStuffToAHiddenSheetWithoutTheUserKnowingIt()
    'turns off screen repainting so the user can't see what you're doing
    'incidentally, this dramatically speeds up processing of your code
    Application.ScreenUpdating = False
    'note that if you're stepping through your code, screenupdating will be true anyway

    'unhide the sheet you want to work with
    Sheets("sheet2").Visible = True
        'do whatever you want here, including selecting cells if you want
        'Scagnelli is right though, only select cells if you have to

    'when you're finished, hide the sheet again
    Sheets("sheet2").Visible = False

    'make sure you turn screenupdating back on, or Excel will be useless
    Application.ScreenUpdating = True
End Sub

Another useful trick if you want your sheets hidden is to set them to xlVeryHidden, which will prevent them from being listed to the user if they try to unhide them through the menu or ribbon.