Windows Forms Modal Form Closes instantly when Base form is not Active - vb.net

Question

I have a Winforms Application which should notify the user when something in a database changes. For that i use Sql-Dependencys, which works fine.
When the Dependency fires i am able to show a form with some Buttons so the user can decide what he wants to do.
After one Button i want to show a Dialog, but the first Dialog always gets closed instantly.
The only fix i found until now is restoring the base form and activating it, but that is not the solution i am looking for.
For the code i am doing the Following:
This Method gets called when something changes in the Database
Private Sub NutzerBenachrichtigen(Aenderung As Aenderung)
If InvokeRequired Then
Me.BeginInvoke(New MethodInvoker(Sub()
ErzeugeBenachrichtigung(Aenderung)
End Sub))
Else
ErzeugeBenachrichtigung(Aenderung)
End If
End Sub
This Method Displays the first form (HeadsUp is taken from this here :https://github.com/glm9637/MaterialWinforms/blob/master/MaterialWinforms/Controls/HeadsUp.cs)
Private Sub ErzeugeBenachrichtigung(ByVal Aenderung As Aenderung)
If Aenderung.istAktuellerBenutzer Then
Dim objHeadsUp As New HeadsUp()
objHeadsUp.Titel = "Neue Aenderung"
If Aenderung.EventTyp.ToLower = "alter" Then
objHeadsUp.Text = String.Format("Du hast etwas an {0} {1} {2} geändert. {3}Willst du etwas dazu schreiben?", _
If(Aenderung.BetroffenesObjekt.EntitaetTyp.Name = New EntitaetTyp.Trigger().Name, "dem", "der"), _
Aenderung.BetroffenesObjekt.EntitaetTyp.Name, Aenderung.BetroffenesObjekt.Name, vbNewLine)
Else
objHeadsUp.Text = String.Format("Du hast {0} {1} {2} erstellt. {3}Willst du etwas dazu schreiben?", _
If(Aenderung.BetroffenesObjekt.EntitaetTyp.Name = New EntitaetTyp.Trigger().Name, "den", "die"), _
Aenderung.BetroffenesObjekt.EntitaetTyp.Name, Aenderung.BetroffenesObjekt.Name, vbNewLine)
End If
objHeadsUp.Tag = Aenderung.BetroffenesObjekt
Dim objButtonSchliessen = New MaterialFlatButton
objButtonSchliessen.Tag = objHeadsUp
objButtonSchliessen.Text = "Schliessen"
AddHandler objButtonSchliessen.Click, AddressOf SchliesseHeadsUp
objHeadsUp.Buttons.Add(objButtonSchliessen)
Dim objButtonHistorie = New MaterialFlatButton
objButtonHistorie.Tag = objHeadsUp
objButtonHistorie.Text = "Historieneintrag"
AddHandler objButtonHistorie.Click, AddressOf HistorienEintragHinzufuegen
objHeadsUp.Buttons.Add(objButtonSchliessen)
Dim objButtonDokumentation = New MaterialFlatButton
objButtonDokumentation.Tag = objHeadsUp
objButtonDokumentation.Text = "Dokumentation"
AddHandler objButtonDokumentation.Click, AddressOf DokumentationBearbeiten
objHeadsUp.Buttons.Add(objButtonSchliessen)
objHeadsUp.Buttons.Add(objButtonHistorie)
objHeadsUp.Buttons.Add(objButtonDokumentation)
objHeadsUp.Show()
ElseIf Aenderung.EventTyp = "CLOSE_MESSAGE" Then
Dim objHeadsUp As New HeadsUp()
objHeadsUp.Titel = "Achtung"
objHeadsUp.Text = "Die Anwendung muss für eine Aktualisierung geschlossen werden."
Dim objButtonSchliessen = New MaterialFlatButton
objButtonSchliessen.Tag = objHeadsUp
objButtonSchliessen.Text = "Anwendung Schliessen"
AddHandler objButtonSchliessen.Click, AddressOf AnwendungSchliessen
objHeadsUp.Buttons.Add(objButtonSchliessen)
objHeadsUp.Show()
Else
If mtc_UebersichtTabControl.SelectedTab.Text = "Aenderung" Then
mAenderungenUebersicht.Aktualisieren()
End If
End If
End Sub
Finally when the "Historieneintrag" Button is pressed this Method gets called:
Private Sub HistorienEintragHinzufuegen(sender As Object, e As EventArgs)
Dim blnNachDialogVerstecken As Boolean = False
Dim objFlatButton As MaterialFlatButton = sender
Dim HeadsUp As HeadsUp = objFlatButton.Tag
Dim Objekt As Entitaet = HeadsUp.Tag
Dim objOldLocation As System.Drawing.Point = Location
HeadsUp.Close()
Dim objDialogContent As New HistorienEintrag()
''Hacky: Ansonsten wird der Dialog sofort geschlossen
If WindowState = FormWindowState.Minimized Or Not Visible Then
Location = New System.Drawing.Point(-Width * 2, -Height - 2)
Me.Show()
blnNachDialogVerstecken = True
End If
Activate()
If MaterialDialog.Show("Neuer Historien Eintrag", objDialogContent, MaterialWinforms.Controls.MaterialDialog.Buttons.OKCancel, MaterialDialog.Icon.Info) = DialogResult.OK Then
Objekt.HistorieSpeichern(objDialogContent.Ergebniss)
End If
If blnNachDialogVerstecken Then
Me.Hide()
Location = objOldLocation
End If
End Sub
In here the first modal Form, so a MessageBox.Show("") or any other form closes Instantly if i don't do the show and activate part.
What am i doing wrong here?

Answer 1

Project > (Project) Properties > Application > Shutdown mode
change from when startup form closes to when last form closes