Problem calling ".Selection.PickObject" from a ShowDialog Form

[MucSt3ve]

I need the possibility to pick element(s) in Revit GUI from a Windows From that ist shown with showdialog.
Eveything is working fine from inside the form to make changes to the revit database with transactions.
But still found no way to allow the user to click elements in the GUI.

Testcode which should allow the user to pick an element an then find the ID in an datagrid on the form

Private Sub cmdMEP_RaumSuchen_Click(sender As Object, e As EventArgs) Handles cmdMEP_RaumSuchen.Click

Me.Hide()

Dim rvtElementRef As Reference
rvtElementRef = m_rvtUidoc.Selection.PickObject(ObjectType.Element, "MEP-Raum wählen")

Dim rvtElement As Element
rvtElement = m_rvtDoc.GetElement(rvtElementRef.ElementId)


Me.ShowDialog()

Dim Row As DataGridViewRow
For Each Row In dbgRaumbuch.Rows
If Row.Cells("MepID").Value.ToString = rvtElement.Id.ToString Then
Row.Selected = True
End If
Next

End Sub

Would be nice if anyone can help me

[sdarali]

I know this is kinda late reply, but I've been looking at the same issue recently and it is not possible to pick objects because non modal Dialog boxes do not allow the Revit interface to behave properly. If you're not in need of transactions to modify or add something then you can use a modal dialog by using form.show instead of form.showdialog

Modal dialogs however cannot use transactions because of some technical reasons, so you can use any Api function that does not require a transaction such as selection, reading parameters or properties.

[arqt49]

Not really, you can invoke a ExternalEvent from a modeless window.
The event can be raise the on a separate thread or, even better, you can implement a async Task.