powershell combobox items to variable - winforms

Question

I am trying to create a powershell Script with a Gui that gives the user a drop list of available drives and then when the user selects the drive and clicks ok the script maps that drive as M:\
But I cant work out how to get the selected item in the combo box to be passed into the variable $MapDrive
#List of Drives To Map
$DriveList = #("0. DGL_Data","1. P1","2. DGLFSG3","3. p3 (TPC)","4. p4","6. p6","7. p7","8. p8","9. p9","10. p10","11. p11","12. p12")
#Displays With Drive to Map
$MapDrive = convert.ToString($Dropdown.SelectedItem)
Function MapDrive {
If ($MapDrive -eq $DriveList[0]){
Write-Output Sucess > "C:\Users\andy.burton\Desktop\Practice Selector\Success.txt"}
ElseIf ($MapDrive -eq $DriveList[1]){
Write-Output BooYah > "C:\Users\andy.burton\Desktop\Practice Selector\Yes.txt"
}
Else {
Write-Output Failure > "C:\Users\andy.burton\Desktop\Practice Selector\Failed.txt"}
}
#test Function
Function test {
Write-Output $MapDrive > "C:\Users\andy.burton\Desktop\Practice Selector\Success.txt"
}
#Function to Create Form
Function GenerateForm {
#Define Drive Selector Main Form
Add-Type -AssemblyName System.Windows.Forms
$DGL = New-Object system.Windows.Forms.Form
$DGL.Text = "DGL Practice Manager"
$DGL.TopMost = $true
$DGL.BackgroundImage = [system.drawing.image]::FromFile("C:\Users\andy.burton\Desktop\Practice Selector\Images\medical.jpg")
$DGL.Icon = New-Object system.drawing.icon("C:\Users\andy.burton\Desktop\Practice Selector\Images\medical2.ico")
$DGL.Width = 600
$DGL.Height = 265
$DGL.MinimizeBox = $False
$DGL.MaximizeBox = $False
#Label to Display Instuctions
$label2 = New-Object system.windows.Forms.Label
$label2.Text = "Select which drive"
$label2.BackColor = "#e4f3fa"
$label2.AutoSize = $true
$label2.Width = 25
$label2.Height = 10
$label2.location = new-object system.drawing.point(20,28)
$label2.Font = "Microsoft Sans Serif,10"
$DGL.controls.Add($label2)
#Dropdown Box For Selecting Practice
$Dropdown = New-Object system.windows.Forms.ComboBox
$Dropdown.BackColor = "#e4f3fa"
$DropDown.DropDownStyle = [System.Windows.Forms.ComboBoxStyle]::DropDownList
$Dropdown.Width = 243
$Dropdown.Height = 20
$Dropdown.location = new-object system.drawing.point(21,73)
$Dropdown.Font = "Microsoft Sans Serif,10"
$DropDown.items.addrange($DriveList)
$DGL.controls.Add($Dropdown)
#Cancel Button to Cancel drive Selection
$Cancelbutton = New-Object system.windows.Forms.Button
$Cancelbutton.Text = "Cancel"
$Cancelbutton.Width = 60
$Cancelbutton.Height = 30
$Cancelbutton.location = new-object system.drawing.point(210,120)
$Cancelbutton.Font = "Microsoft Sans Serif,10"
$DGL.CancelButton = $Cancelbutton
$CancelButton.Add_Click({ $DGL.close();[System.Windows.Forms.Application]::Exit($null)})
$DGL.controls.Add($Cancelbutton)
#OK Button to Select Drive
$OKbutton = New-Object system.windows.Forms.Button
$OKbutton.Text = "OK"
$OKbutton.Width = 60
$OKbutton.Height = 30
$OKbutton.location = new-object system.drawing.point(140,120)
$OKbutton.Font = "Microsoft Sans Serif,10"
$DGL.AcceptButton = $OKbutton
$MapDrive = convert.ToString($Dropdown.SelectedItem)
#On click call PracticeSelectedCallBack to launch the application
$OKbutton.Add_Click({test ; $DGL.close()})
$DGL.controls.Add($OKbutton)
#Display the Form
$DGL.Add_Shown({$DGL.Activate()})
$DGL.ShowDialog()
}
GenerateForm
I also want to hide the powershell window but not the gui I have tried -window hidden but that hid everything

Answer 1

The ComboBox has several events that you can tie into that will do various things. One of the events is a SelectedIndexChanged. You can add that event to your ComboBox object and update $MapDrive
This code $MapDrive = convert.ToString($Dropdown.SelectedItem) will only fire once during the initial compile. You have to use events to trigger code changes after compile during runtime.
Also, in Powershell you can use the following command [System.Windows.Forms.ComboBox] | gm to get a list of the methods, and properties of the object. You can use [System.Windows.Forms.checkedlistbox].GetEvents() to get a list of events of an object.