ScrolledWindow not showing scollbars when used with PyCollapsiblePane

Question

I ran into a problem regarding the behaviour of a wx.ScrolledWindow that contains a PyCollapsiblePane. I took the example-code within wx.lib.agw.pycollapsiblepane and modified it slightly (usage of a wx.ScrolledWindow und reaction to collapse-/expand- events):

import wx
import wx.lib.agw.pycollapsiblepane as PCP

class MyFrame(wx.Frame):

    def __init__(self, parent):

        wx.Frame.__init__(self, parent, -1, size=wx.Size(600, 200), name="PyCollapsiblePane Demo")

        self.panel = wx.ScrolledWindow(self)

        title = wx.StaticText(self.panel, label="PyCollapsiblePane")
        title.SetFont(wx.Font(18, wx.FONTFAMILY_SWISS, wx.FONTSTYLE  _NORMAL, wx.FONTWEIGHT_BOLD))
        title.SetForegroundColour("blue")

        self.cp = cp = PCP.PyCollapsiblePane(self.panel, label="Some Data", style=wx.CP_DEFAULT_STYLE )
        self.MakePaneContent(cp.GetPane())
        self.panel.Bind(wx.EVT_COLLAPSIBLEPANE_CHANGED, self.OnPaneChanged, self.cp)

        sizer = wx.BoxSizer(wx.VERTICAL)
        sizer.Add(title, 0, wx.ALL, 25)
        sizer.Add(cp, 0, wx.RIGHT | wx.LEFT | wx.EXPAND, 25)

        width, height = sizer.GetMinSize()
        self.panel.SetScrollbars(10, 10, width/10, height/10)
        self.panel.SetSizer(sizer)
        sizer.Layout()

    def OnPaneChanged(self, event):
        print("Re-Layout")
        self.panel.Layout()

    def MakePaneContent(self, pane):
        ''' Just makes a few controls to put on `PyCollapsiblePane`. '''

        nameLbl = wx.StaticText(pane, -1, "Name:")
        name = wx.TextCtrl(pane, -1, "");

        addrLbl = wx.StaticText(pane, -1, "Address:")
        addr1 = wx.TextCtrl(pane, -1, "");
        addr2 = wx.TextCtrl(pane, -1, "");

        cstLbl = wx.StaticText(pane, -1, "City, State, Zip:")
        city  = wx.TextCtrl(pane, -1, "", size=(150,-1));
        state = wx.TextCtrl(pane, -1, "", size=(50,-1));
        zip   = wx.TextCtrl(pane, -1, "", size=(70,-1));

        addrSizer = wx.FlexGridSizer(cols=2, hgap=5, vgap=5)
        addrSizer.AddGrowableCol(1)
        addrSizer.Add(nameLbl, 0, wx.ALIGN_RIGHT | wx.ALIGN_CENTER_VERTICAL)
        addrSizer.Add(name, 0, wx.EXPAND)
        addrSizer.Add(addrLbl, 0, wx.ALIGN_RIGHT | wx.ALIGN_CENTER_VERTICAL)
        addrSizer.Add(addr1, 0, wx.EXPAND)
        addrSizer.Add((5,5))
        addrSizer.Add(addr2, 0, wx.EXPAND)

        addrSizer.Add(cstLbl, 0, wx.ALIGN_RIGHT | wx.ALIGN_CENTER_VERTICAL)

        cstSizer = wx.BoxSizer(wx.HORIZONTAL)
        cstSizer.Add(city, 1)
        cstSizer.Add(state, 0, wx.LEFT | wx.RIGHT, 5)
        cstSizer.Add(zip)
        addrSizer.Add(cstSizer, 0, wx.EXPAND)

        border = wx.BoxSizer()
        border.Add(addrSizer, 1, wx.EXPAND | wx.ALL, 5)
        pane.SetSizer(border)


# our normal wxApp-derived class, as usual

app = wx.App(0)

frame = MyFrame(None)
app.SetTopWindow(frame)
frame.Show()

app.MainLoop()

When the collapsible pane is expanded I expect the scrolled window to add scrollbars because not everything can be seen in the frame. But the current behaviour is that no scrollbars appear. Only when the whole window is manually resized with the mouse the scrollbars start to appear (they also don't disappear when the collapsible pane is collapsed again).

Things I tried so far:

• self.Layout() instead of self.panel.Layout()
• different styles for PCP.PyCollapsiblePane
• initially expand the pane

I am using:

• wxPython 4.0.3
• Python 2.7.15

Thanks for your help.

Answer 1

use

self.panel.PostSizeEvent()