PowerShell GUI - Setting "button.Add_MouseEnter" actions in a function - powershell

Question

I'm creating a small PowerShell GUI with a buttons to quickly run various powershell commands. I've got the general layout how I want it, but now I'm trying to simplify my code by using a button building function.
I don't have an issue setting assorted traits like "Button.Text", "Button.SetToolTip", or "Button.Add_Click" in a separate function, but I'm having issues setting the "Button.Add_MouseEnter" and "Button.Add_MouseLeave" aspects in a stand-alone function. The code compiles fine, but when I hover over the button in the gui I get the following error (similar errors for lines 8-10)
"The property 'BackColor' cannot be found on this object. Verify that the property exists and can be set.
At line:7 char:30
$tButton.Add_MouseEnter({$tButton.BackColor = '#990000'})
CategoryInfo : InvalidOperation: (:) [], RuntimeException
FullyQualifiedErrorId : PropertyNotFound"
I tried creating the button object fully in the function and returning the button, which would set all the button traits correctly but still gives the same error when the mouse passes over. I think I may need to pass the button object to the function/return the button differently (depending on which code 1st or 2nd), but I don't know. I thought perhaps binding the parameters with [CmdletBinding()] but the error still comes up (I probably don't understand that as well as I should) Any insight would be appreciated
===== Initial Code =====
`
[void] [System.Reflection.Assembly]::LoadWithPartialName("System.Windows.Forms")
[void] [System.Reflection.Assembly]::LoadWithPartialName("System.Drawing")
Clear-Host
function Set-Hover ($tButton){
$tButton.Add_MouseEnter({$tButton.BackColor = '#990000'})
$tButton.Add_MouseEnter({$tButton.ForeColor = '#000000'})
$tButton.Add_MouseLeave({$tButton.BackColor = '#000000'})
$tButton.Add_MouseLeave({$tButton.ForeColor = '#FFFFFF'})
}
$Window = New-Object System.Windows.Forms.Form
$Window.ClientSize = New-Object System.Drawing.Size(100, 50)
$Global:Button = New-Object 'system.Windows.Forms.Button'
$Button.Size = New-Object System.Drawing.Point(75,40)
$Button.Location = New-Object System.Drawing.Point(5, 5)
$Button.text = "Button"
$Button.BackColor = '#000000'
$Button.ForeColor = '#FFFFFF'
Set-Hover -tButton $Button
$Window.Controls.Add($Button)
<# The code works when the Mouse_Enter/Leave lines are here, not in a function
$Button.Add_MouseEnter({$Button.BackColor = '#990000'})
$Button.Add_MouseEnter({$Button.ForeColor = '#000000'})
$Button.Add_MouseLeave({$Button.BackColor = '#000000'})
$Button.Add_MouseLeave({$Button.ForeColor = '#FFFFFF'})
#>
$Window.ShowDialog()
`
===== Second Code =====
[void] [System.Reflection.Assembly]::LoadWithPartialName("System.Windows.Forms")
[void] [System.Reflection.Assembly]::LoadWithPartialName("System.Drawing")
Clear-Host
function Set-Hover {
$tButton = New-Object 'system.Windows.Forms.Button'
$tButton.Size = New-Object System.Drawing.Point(75,40)
$tButton.Location = New-Object System.Drawing.Point(5, 5)
$tButton.text = "Text"
$tButton.BackColor = '#FFFFFF'
$tButton.ForeColor = '#000000'
$tButton.Add_MouseEnter({$tButton.BackColor = '#990000'})
$tButton.Add_MouseEnter({$tButton.ForeColor = '#000000'})
$tButton.Add_MouseLeave({$tButton.BackColor = '#000000'})
$tButton.Add_MouseLeave({$tButton.ForeColor = '#FFFFFF'})
$tButton
}
$Window = New-Object System.Windows.Forms.Form
$Window.ClientSize = New-Object System.Drawing.Size(100, 50)
$Button1 = Set-Hover
$Window.Controls.Add($Button1)
<# The code works when the Mouse_Enter/Leave lines are here, not in a function
$Button.Add_MouseEnter({$Button.BackColor = '#990000'})
$Button.Add_MouseEnter({$Button.ForeColor = '#000000'})
$Button.Add_MouseLeave({$Button.BackColor = '#000000'})
$Button.Add_MouseLeave({$Button.ForeColor = '#FFFFFF'})
#>
$Window.ShowDialog()

Answer 1

You need to define the button in the form code, not create a new one inside the function when the mouse hovers over it (or away from it).
If you do want to use a function for this, change your function to accept parameters (the first is the button object itself, the second a switch to determine if it is an MouseEnter or MouseLeave event)
Also, better not use the old [void] [System.Reflection.Assembly]::LoadWithPartialName("System.Windows.Forms") syntax anymore.
Here's your code revised:
Add-Type -AssemblyName System.Windows.Forms
Add-Type -AssemblyName System.Drawing
function Set-Hover {
param (
[System.Windows.Forms.Button]$ButtonObject,
[switch] $MouseEnter
)
if ($MouseEnter) {
$bkColor = '#990000'
$fgColor = '#000000'
}
else {
$bkColor = '#000000'
$fgColor = '#FFFFFF'
}
$ButtonObject.BackColor = $bkColor
$ButtonObject.ForeColor = $fgColor
}
$Window = New-Object System.Windows.Forms.Form
$Window.Size = New-Object System.Drawing.Size(250, 250)
$Button = New-Object System.Windows.Forms.Button
$Button.Size = New-Object System.Drawing.Point(75,40)
$Button.Location = New-Object System.Drawing.Point(5, 5)
$Button.Text = "Button"
$Button.BackColor = '#000000'
$Button.ForeColor = '#FFFFFF'
# inside an event handler, you can refer to the current object with keyword $this
$Button.Add_MouseEnter({ Set-Hover -ButtonObject $this -MouseEnter })
$Button.Add_MouseLeave({ Set-Hover -ButtonObject $this })
$Window.Controls.Add($Button)
$Window.ShowDialog()
# important: Remove the form from memory when done with it
$Window.Dispose()