When an auto-hidden toolwindow contains a WinForms toolstrip via WindowsFormsHost, expanding the toolwindow via clicking on its tab, then interacting with the toolstrip only, will result in the toolwindow collapsing if a dialog is opened. This also results in the dialog being auto-closed as well.
I would guess that the same problem would also happen for MeuStrips in similar circumstances.
1) This only occurs if the toolwindow does not contain focus - if you click on a normal child control prior to opening dialog via toolstrip (e.g. in below example, a treenode) , then the toolwindow remains correctly expanded.
2) This only happens if the suggested DockSite.UseHostedPopups and DockSite.IsLiveSplittingEnabled are set to false. If this is not done, then the toolwindow remains expanded as it should be, although then you have the rendering problems that disabling those solve.
3) It doesn't matter whether the dialog opened is WinForms or WPF.
Below is code to reproduce the problem - add the Sub to MainControl of SimpleIDE Dock in the demo, and call at the end of construction.
Once run, click on the extra auto-hidden toolwindow's tab to expand, then click the only toolstripbutton on the toolstrip.
Private Sub DockTest() Me.dockSite.UseHostedPopups = False Me.dockSite.IsLiveSplittingEnabled = False Dim f As New System.Windows.Forms.Form Dim tv As New System.Windows.Forms.TreeView Dim tn As New System.Windows.Forms.TreeNode("A Node") f.FormBorderStyle = Forms.FormBorderStyle.None tv.Location = New Drawing.Point(0, 25) tv.Nodes.Add(tn) tv.Dock = Forms.DockStyle.Fill f.Controls.Add(tv) Dim ts As New System.Windows.Forms.ToolStrip Dim tb As New System.Windows.Forms.ToolStripButton tb.Text = "A Button" tb.DisplayStyle = Forms.ToolStripItemDisplayStyle.Text ts.Items.Add(tb) ts.Dock = Forms.DockStyle.Top ts.Location = New Drawing.Point(0, 0) f.Controls.Add(ts) AddHandler tb.Click, Sub(ByVal sender As Object, ByVal e As EventArgs) System.Windows.Forms.MessageBox.Show("Hello") End Sub Dim wfh As New System.Windows.Forms.Integration.WindowsFormsHost Dim tw As New ToolWindow(dockSite, "1", "window1", Nothing, wfh) InteropFocusTracking.SetIsEnabled(wfh, True) f.Dock = Forms.DockStyle.Fill f.TopLevel = False wfh.Child = f tw.Activate() tw.Dock(tabbedMdiHost, ActiproSoftware.Windows.Controls.Side.Bottom) tw.AutoHide(ActiproSoftware.Windows.Controls.Side.Bottom) End Sub