Watch Window

A watch is a variable or expression that has been placed in the window to enable you to monitor its value.
Lets you watch the values of variables and expressions as your code executes.
When your application enters break mode, the watch expressions you select appear in a window allowing you to observe their values etc. It is also possible to set up conditional watches.
This window is automatically updated after each line of code is executed.

Watches Window

Although it is labelled as Watch Window the actual window displays Watches Window.

Expression - Lists the watch expression with the Watch icon, on the left.
Value - List the value of the expression at the time of the transition to break mode.
Type - Lists the expression type.
Context - Lists the context of the watch expression.
You can close the window by clicking the Close box. If the Close box is not visible, double-click the Title bar to make the Close box visible, then click it.

This window shows all the watches that have been created.
Lets you pause the program when a variable value changes.

Appears automatically when watch expressions are defined in the project.
You can change the size of the column headers by dragging its border to the right to make it larger or to the left to make it smaller.
Close the window by clicking the Close box. If the Close box is not visible, double-click the Title bar to make the Close box visible, then click it.
You can edit a value and then press ENTER, the UP ARROW key, the DOWN ARROW key, TAB, SHIFT+TAB, or click somewhere on the screen to validate the change. If the value is illegal, the Edit field remains active and the value is highlighted. A message box describing the error also appears. Cancel a change by pressing ESC.
If the context of the expression isn't in scope when going to break mode, the current value isn't displayed.

Add A Watch

3 different types of watches
highlight a variable and drag it straight in
To add a watch select (Debug > Add Watch).

Expression -
Context - After adding a watch you can use these drop-downs to change the scope to "Full scope" if originally entered as local scope.
Watch Expression - Adds the expression so the value can be watched during execution. Same as Local Window.
Break When Value is True - Adds the expression so the value can be watched and execution will enter break mode if the value of the expression is true
Break When Value Changes - Add the expression so the value can be watched and execution will enter break mode if the value of the expression changes

Drag and Drop

Variables can be added by dragging and dropping them into the window. It is easy to watch individual variables.
Drag a selected variable to the Immediate window or the Watch window.

Quick Watch

This is a feature you can use to check the value of a variable or expression quickly while in break mode.
Place the insertion point over the variable name and select (Debug > Quick Watch) or alternatively press (Shift + F9).
You can highlight complete expressions

Another way to get values for expressions and variables quickly is to enable the Auto Data Tips from the (Tools > Options)(Editor tab).
With this feature enabled when you place the mouse over a variable or select an expression and place the mouse over the expression a tool tip will appear after a sort delay displaying the current value.

To view the value of variables during execution or break mode hover the cursor over the variable within the procedure or expression. Entire expressions can be evaluated by highlighting the expression with the cursor and hovering.

Remove a Watch

Screen shots of how to remove watches (especially break when value is true)

3 different icons in window
Delete it by clicking on the far left and pressing delete

Remember

The Watch Window does not show more than 256 class objects in a collection !!!
Create a simple class and have code to test this.

Adding Using Code

You can use Application.SendKeys to add Watches
The VBE must be in focus when the code is run. You can either do this manually or use the VBIDE object to set the focus.
Call AddWatch sub with the specified arguments.
You can add these to a sub you call when you start a new session, as demonstrated in my "HelloNewSession()"

Enum enumWatchType 
    WatchExpression 
    BreakWhenTrue 
    BreakWhenChange 
End Enum 

Enum enumProceduresType 
    AllProcedures 
    Caller 
End Enum 

Enum enumModuleType 
    AllModules 
    CurrentModule 
    ThisWorkbook 
End Enum 

Public testVar As Boolean 
Sub HelloNewSession() 
    AddWatch "testVar = True", AllProcedures, CurrentModule, BreakWhenTrue 
    testVar = True 
End Sub 

Sub AddWatch( _ 
    expression As String, _ 
    Optional proceduresType As enumProceduresType = enumProceduresType.Caller, _ 
    Optional moduleType As enumModuleType = enumModuleType.CurrentModule, _ 
    Optional watchType As enumWatchType = enumWatchType.WatchExpression) 

    Dim i As Long 

    Application.SendKeys "%DA" 
    Application.SendKeys getEscapedSendkeysText(expression) 
    If proceduresType = enumProceduresType.AllProcedures Then 
        Application.SendKeys "%p" 
        For i = 1 To 1000 'You could use VBIDE to count the valid types to actually scroll up the right number of times!  
            Application.SendKeys "{UP}" 
        Next 
    End If 
    If moduleType = enumModuleType.AllModules Then 
        Application.SendKeys "%m" 
        For i = 1 To 1000 'You could use VBIDE to count the valid types to actually scroll up the right number of times!  
            Application.SendKeys "{UP}" 
        Next 
    ElseIf moduleType = enumModuleType.ThisWorkbook Then 
        Application.SendKeys "%m" 
        For i = 1 To 1000 'You could use VBIDE to count the valid types to actually scroll up the right number of times!  
            Application.SendKeys "{DOWN}" 
        Next 
    End If 
    Select Case watchType 
        Case enumWatchType.WatchExpression 
            Application.SendKeys "%w" 
        Case enumWatchType.BreakWhenTrue 
            Application.SendKeys "%t" 
        Case enumWatchType.BreakWhenChange 
            Application.SendKeys "%c" 
    End Select 

    Application.SendKeys "~" 
End Sub 

Function getEscapedSendkeysText(ByVal text As String) As String 
    Dim char As String, i As Long 
    Const chars As String = "~%+^()[]" 
    For i = 1 To Len(chars) 
        char = Mid$(chars, i, 1) 
        text = Replace(text, char, "{" & char & "}") 
    Next 
    getEscapedSendkeysText = text 
End Function