Index: ActiviteitenOpvolging/ActiviteitenOpvolging/screens/IActivityMainForm.vb
===================================================================
diff -u
--- ActiviteitenOpvolging/ActiviteitenOpvolging/screens/IActivityMainForm.vb	(revision 0)
+++ ActiviteitenOpvolging/ActiviteitenOpvolging/screens/IActivityMainForm.vb	(revision 1726)
@@ -0,0 +1,7 @@
+Public Interface IActivityMainForm
+    ''' <summary>
+    ''' Gets the currently selected activity.
+    ''' </summary>
+    ''' <returns></returns>
+    Function GetCurrentlySelectedActivity As IActivity
+End Interface
Index: ActiviteitenOpvolging/ActiviteitenOpvolging/domain/classes/implementations/Employee.vb
===================================================================
diff -u -r1724 -r1726
--- ActiviteitenOpvolging/ActiviteitenOpvolging/domain/classes/implementations/Employee.vb	(.../Employee.vb)	(revision 1724)
+++ ActiviteitenOpvolging/ActiviteitenOpvolging/domain/classes/implementations/Employee.vb	(.../Employee.vb)	(revision 1726)
@@ -7,7 +7,7 @@
     Public Property FirstName As String Implements IEmployee.FirstName
     Public Property LastName As String Implements IEmployee.LastName
     Public Property Initials As String Implements IEmployee.Initials
-    Public Property currentActivity As IActivity Implements IEmployee.currentActivity
+    Public Property CurrentActivity As IActivity Implements IEmployee.CurrentActivity
 
     Public Overrides Function Equals(obj As Object) As Boolean Implements IEmployee.Equals
         If Not TypeOf obj Is IEmployee Then
Index: ActiviteitenOpvolging/ActiviteitenOpvolging/domain/classes/IEmployee.vb
===================================================================
diff -u -r1724 -r1726
--- ActiviteitenOpvolging/ActiviteitenOpvolging/domain/classes/IEmployee.vb	(.../IEmployee.vb)	(revision 1724)
+++ ActiviteitenOpvolging/ActiviteitenOpvolging/domain/classes/IEmployee.vb	(.../IEmployee.vb)	(revision 1726)
@@ -5,7 +5,7 @@
     Property LastName As String
     Property Initials As String
 
-    Property currentActivity As IActivity
+    Property CurrentActivity As IActivity
 
     Function Equals(obj As Object) As Boolean
 End Interface
Index: ActiviteitenOpvolging/ActiviteitenOpvolging/screens/employee/details/EmployeeDetailUserControl.vb
===================================================================
diff -u -r1725 -r1726
--- ActiviteitenOpvolging/ActiviteitenOpvolging/screens/employee/details/EmployeeDetailUserControl.vb	(.../EmployeeDetailUserControl.vb)	(revision 1725)
+++ ActiviteitenOpvolging/ActiviteitenOpvolging/screens/employee/details/EmployeeDetailUserControl.vb	(.../EmployeeDetailUserControl.vb)	(revision 1726)
@@ -64,13 +64,13 @@
         NameLabel.Text = $"{employee.FirstName} {employee.LastName}"
 
         'If activity is Nothing, empty the labels.
-        If IsNothing(employee.currentActivity) Then
+        If IsNothing(employee.CurrentActivity) Then
             'Nothing, empty labels.
             StatusLabel.Text = String.Empty
             BatchLabel.Text = String.Empty
             ActivityNameLabel.Text = String.Empty
         Else
-            Dim activity = employee.currentActivity
+            Dim activity = employee.CurrentActivity
             'Set activity status according to state.
             Select Case activity.Status
                 Case ActivityStateEnum.Started
@@ -82,12 +82,26 @@
                 Case ActivityStateEnum.Defaulted
                     StatusLabel.Text = "Beschikbaar"
             End Select
-           ' BatchLabel.Text = activity.bat
+            BatchLabel.Text = activity.WorkItem.BatchVisual
             ActivityNameLabel.Text = activity.Label
         End If
 
+        'Get the activity selected in one of the grids.
+        Dim currentlySelectedActivity = _parentUserControl.GetCurrentlySelectedActivity()
 
-        'todo enable status of buttons.
+        'Update enable status of buttons.
+        If IsNothing(employee.CurrentActivity) Then
+            'No current activity.
+            StopButton.visible = False
+            FinishButton.visible = False
+            'Start button visible when the selected activity can be started (you shouldn't be able to select an activity that can't be started).
+            StartButton.visible = Not IsNothing(currentlySelectedActivity)
+        Else
+            'An activity in progress can be stopped or finished.
+            StartButton.visible = False
+            StopButton.visible = True
+            FinishButton.visible = True
+        End If
     End Sub
 
     Private Sub RemoveEmployeeButton_Click(sender As Object, e As EventArgs) Handles RemoveEmployeeButton.Click
Index: ActiviteitenOpvolging/ActiviteitenOpvolging/screens/employee/details/IEmployeeDetailParentUserControl.vb
===================================================================
diff -u -r1721 -r1726
--- ActiviteitenOpvolging/ActiviteitenOpvolging/screens/employee/details/IEmployeeDetailParentUserControl.vb	(.../IEmployeeDetailParentUserControl.vb)	(revision 1721)
+++ ActiviteitenOpvolging/ActiviteitenOpvolging/screens/employee/details/IEmployeeDetailParentUserControl.vb	(.../IEmployeeDetailParentUserControl.vb)	(revision 1726)
@@ -1,4 +1,7 @@
 Public Interface IEmployeeDetailParentUserControl
+
+    Function GetCurrentlySelectedActivity() As IActivity
+
     ''' <summary>
     ''' Get the employee.
     ''' </summary>
Index: ActiviteitenOpvolging/ActiviteitenOpvolging/screens/IEmployeesMainForm.vb
===================================================================
diff -u -r1721 -r1726
--- ActiviteitenOpvolging/ActiviteitenOpvolging/screens/IEmployeesMainForm.vb	(.../IEmployeesMainForm.vb)	(revision 1721)
+++ ActiviteitenOpvolging/ActiviteitenOpvolging/screens/IEmployeesMainForm.vb	(.../IEmployeesMainForm.vb)	(revision 1726)
@@ -1,4 +1,5 @@
 Public Interface IEmployeesMainForm
+    Inherits IActivityMainForm
     ''' <summary>
     ''' Gets all the employees.
     ''' </summary>
Index: ActiviteitenOpvolging/ActiviteitenOpvolging/screens/employee/IEmployeeUserControl.vb
===================================================================
diff -u -r1717 -r1726
--- ActiviteitenOpvolging/ActiviteitenOpvolging/screens/employee/IEmployeeUserControl.vb	(.../IEmployeeUserControl.vb)	(revision 1717)
+++ ActiviteitenOpvolging/ActiviteitenOpvolging/screens/employee/IEmployeeUserControl.vb	(.../IEmployeeUserControl.vb)	(revision 1726)
@@ -1,7 +1,11 @@
 Public Interface IEmployeeUserControl
     ''' <summary>
-    ''' Refresh the data of the employee.
+    ''' Triggered when the selected activity changes.
     ''' </summary>
-    ''' <returns>Whether or not it was successful</returns>
-    Function RefreshData() As Boolean
+    Sub SelectedActivityChanged()
+
+    ''' <summary>
+    ''' Triggered when the amount of selected user changes.
+    ''' </summary>
+    Sub SelectedEmployeeChanged()
 End Interface
Index: ActiviteitenOpvolging/ActiviteitenOpvolging/ActiviteitenOpvolgingForm.vb
===================================================================
diff -u -r1723 -r1726
--- ActiviteitenOpvolging/ActiviteitenOpvolging/ActiviteitenOpvolgingForm.vb	(.../ActiviteitenOpvolgingForm.vb)	(revision 1723)
+++ ActiviteitenOpvolging/ActiviteitenOpvolging/ActiviteitenOpvolgingForm.vb	(.../ActiviteitenOpvolgingForm.vb)	(revision 1726)
@@ -68,8 +68,11 @@
         Return _domainController.GiveWorkItems(gridNumber)
     End Function
 
+    Private _selectedActivity As IActivity
     ''' <inheritdoc/>
     Public Sub ChangeSelectedActivity(activity As IActivity, gridNumber As Integer) Implements IWorkItemsMainForm.ChangeSelectedActivity
+        'Store the activity.
+        _selectedActivity = activity
         'If the activity is Nothing, no activity was selected, meaning that everything should be cleared.
         If activity Is Nothing Then
             'Clear selection for every grid user control.
@@ -81,8 +84,15 @@
                 If Not control.GridNumber = gridNumber Then control.RemoveSelection()
             Next
         End If
+        'Update employee user controls.
+        _employeeUserControls.ForEach(Sub(employeeUserControl) employeeUserControl.SelectedActivityChanged())
     End Sub
 
+    ''' <inheritdoc/>
+    Public Function GetCurrentlySelectedActivity() As IActivity Implements IActivityMainForm.GetCurrentlySelectedActivity
+        Return _selectedActivity
+    End Function
+
     Private Sub RefreshButton_Click(sender As Object, e As EventArgs) Handles RefreshButton.Click
         RefreshButton.Enabled = False
         RefreshUserGridsData()
@@ -145,20 +155,21 @@
     Public Sub SelectEmployee(employeeIndex As Integer, employee As IEmployee) Implements IEmployeesMainForm.SelectEmployee
         'Call function in dc.
         _domainController.SelectEmployee(employeeIndex, employee)
-        'Update all employee user controls.
-        _employeeUserControls.ForEach(Sub(employeeUserControl) employeeUserControl.RefreshData())
+        'Send message that the selected employee changed to all user controls.
+        _employeeUserControls.ForEach(Sub(employeeUserControl) employeeUserControl.SelectedEmployeeChanged())
     End Sub
 
     ''' <inheritdoc/>
     Public Sub DeselectEmployee(employeeIndex As Integer) Implements IEmployeesMainForm.DeselectEmployee
         _domainController.DeselectEmployee(employeeIndex)
-        'Update all employee user controls.
-        _employeeUserControls.ForEach(Sub(employeeUserControl) employeeUserControl.RefreshData())
+        'Send message that the selected employee changed to all user controls.
+        _employeeUserControls.ForEach(Sub(employeeUserControl) employeeUserControl.SelectedEmployeeChanged())
     End Sub
 
     ''' <inheritdoc/>
     Public Function GetSelectedEmployee(employeeIndex As Integer) As IEmployee Implements IEmployeesMainForm.GetSelectedEmployee
         Return _domainController.GetSelectedEmployee(employeeIndex)
     End Function
+
 #End Region
 End Class
Index: ActiviteitenOpvolging/ActiviteitenOpvolging/ActiviteitenOpvolging.vbproj
===================================================================
diff -u -r1721 -r1726
--- ActiviteitenOpvolging/ActiviteitenOpvolging/ActiviteitenOpvolging.vbproj	(.../ActiviteitenOpvolging.vbproj)	(revision 1721)
+++ ActiviteitenOpvolging/ActiviteitenOpvolging/ActiviteitenOpvolging.vbproj	(.../ActiviteitenOpvolging.vbproj)	(revision 1726)
@@ -126,6 +126,7 @@
     <Compile Include="screens\employee\picker\IEmployeePickerParentUserControl.vb" />
     <Compile Include="screens\employee\picker\IEmployeePickerUserControl.vb" />
     <Compile Include="screens\employee\IRefreshableUserControl.vb" />
+    <Compile Include="screens\IActivityMainForm.vb" />
     <Compile Include="screens\IEmployeesMainForm.vb" />
     <Compile Include="screens\employee\IEmployeeUserControl.vb" />
     <Compile Include="screens\IWorkItemsMainForm.vb" />
Index: ActiviteitenOpvolging/ActiviteitenOpvolging/screens/employee/EmployeeUserControl.vb
===================================================================
diff -u -r1723 -r1726
--- ActiviteitenOpvolging/ActiviteitenOpvolging/screens/employee/EmployeeUserControl.vb	(.../EmployeeUserControl.vb)	(revision 1723)
+++ ActiviteitenOpvolging/ActiviteitenOpvolging/screens/employee/EmployeeUserControl.vb	(.../EmployeeUserControl.vb)	(revision 1726)
@@ -54,26 +54,13 @@
         'Border color.
         Dim borderColor = ConfigsLoader.ColorsUsers(EmployeeIndex)
         'Border thickness.
-        Dim borderThickness = 5I
+        Const borderThickness As Integer = 5I
         'Border rectangle.
         Dim borderRectangle = Me.ClientRectangle
         'Draw the border.
         e.Graphics.DrawRectangle(New Pen(borderColor, borderThickness), borderRectangle)
     End Sub
 
-    ''' <inheritdoc/>
-    Public Function RefreshData() As Boolean Implements IEmployeeUserControl.RefreshData
-        Try
-            'Refresh the data on the current user control.
-            _currentUserControl.RefreshData()
-            'Refresh succesfull.
-            Return True
-        Catch ex As Exception
-            'Failed to retrieve update with data.
-            Return False
-        End Try
-    End Function
-
 #Region "Employee picking"
     ''' <inheritdoc/>
     Public Function GetAllEmployees() As ICollection(Of IEmployee) Implements IEmployeePickerParentUserControl.GetAllEmployees
@@ -92,9 +79,22 @@
         End Try
     End Sub
 
+    ''' <inheritdoc/>
+    Public Sub SelectedEmployeeChanged() Implements IEmployeeUserControl.SelectedEmployeeChanged
+        Try
+            'If the current user control is to select the employee, make it refresh.
+            If TypeOf _currentUserControl Is EmployeePickerUserControl Then
+                _currentUserControl.RefreshData()
+            End If
+        Catch ex As Exception
+            MessageBox.Show($"Could not update after employee selection changed.{vbNewLine}{ex.Message}", "An error occured...", MessageBoxButtons.OK, MessageBoxIcon.Error)
+        End Try
+    End Sub
+
 #End Region
 
 #Region "Employee details"
+
     ''' <inheritdoc/>
     Public Function FetchEmployee() As IEmployee Implements IEmployeeDetailParentUserControl.FetchEmployee
         Return _parentForm.GetSelectedEmployee(EmployeeIndex)
@@ -107,13 +107,30 @@
             _parentForm.DeselectEmployee(EmployeeIndex)
 
             'Switch to employee picker user control.
-            SwitchUserControl(new EmployeePickerUserControl(Me))
+            SwitchUserControl(New EmployeePickerUserControl(Me))
         Catch ex As Exception
             MessageBox.Show($"Could not deselect employee.{vbNewLine}{ex.Message}", "An error occured...", MessageBoxButtons.OK, MessageBoxIcon.Error)
         End Try
     End Sub
 
     ''' <inheritdoc/>
+    Public Sub SelectedActivityChanged() Implements IEmployeeUserControl.SelectedActivityChanged
+        Try
+            'If the current user control is to select the employee, make it refresh.
+            If TypeOf _currentUserControl Is EmployeeDetailUserControl Then
+                _currentUserControl.RefreshData()
+            End If
+        Catch ex As Exception
+            MessageBox.Show($"Could not update after activity selection changed.{vbNewLine}{ex.Message}", "An error occured...", MessageBoxButtons.OK, MessageBoxIcon.Error)
+        End Try
+    End Sub
+
+    ''' <inheritdoc/>
+    Public Function GetCurrentlySelectedActivity() As IActivity Implements IEmployeeDetailParentUserControl.GetCurrentlySelectedActivity
+       Return _parentForm.GetCurrentlySelectedActivity()
+    End Function
+
+    ''' <inheritdoc/>
     Public Sub StartActivity() Implements IEmployeeDetailParentUserControl.StartActivity
         Throw New NotImplementedException
     End Sub
@@ -130,8 +147,9 @@
 #End Region
 
     ''' <summary>
-    ''' Swtich to another user control on the screen.
+    ''' Switch to another user control on the screen.
     ''' </summary>
+    ''' <typeparam name="T">Must be a refreshable user control</typeparam>
     ''' <param name="userControl"></param>
     Private Sub SwitchUserControl(Of T As {IRefreshableUserControl, UserControl})(userControl As T)
         'Set current user control.