SplitterWindow sash not visible on Windows

[jhg-goow]

No matter what style(s) I enable, the sash is never visible. I’m using wxFormBuilder to create the UI. Everything works as expected, the only problem is the sash isn’t visible.

I can only embed one image, so I’ll add a screenshot in a reply.

Here’s the structure in wxFormBuilder:

And all mentions of the Splitter in the generated Frame code:

        self.m_splitter1 = wx.SplitterWindow( self, wx.ID_ANY, wx.DefaultPosition, wx.DefaultSize, wx.SP_3D|wx.SP_THIN_SASH )
        self.m_splitter1.SetSashGravity( 0.5 )
        self.m_splitter1.Bind( wx.EVT_IDLE, self.m_splitter1OnIdle )
        self.m_splitter1.SetMinimumPaneSize( 50 )
...
        self.m_panel1 = wx.Panel( self.m_splitter1, wx.ID_ANY, wx.DefaultPosition, wx.DefaultSize, wx.TAB_TRAVERSAL )
...
        self.m_panel2 = wx.Panel( self.m_splitter1, wx.ID_ANY, wx.DefaultPosition, wx.DefaultSize, wx.TAB_TRAVERSAL )
...
        self.m_splitter1.SplitHorizontally( self.m_panel1, self.m_panel2, 0 )
        bSizer7.Add( self.m_splitter1, 1, wx.EXPAND, 5 )
...
    def m_splitter1OnIdle( self, event ):
        self.m_splitter1.SetSashPosition( 0 )
        self.m_splitter1.Unbind( wx.EVT_IDLE )

Any suggestions on how to get the sash to be visible?

[jhg-goow]

Screenshot showing the sash is there and functional, just not visible.

[DietmarSchwertberger]

Unfortunately that’s now the standard on Windows. If you don’t know that there is a splitter, you’re lost…

[jhg-goow]

Ah yes, “broken as designed”. Invented at IBM in the '70s but embraced by all software manufacturers over time -

[qaz1010203044]

Hi, I am also working on Windows and noticed a similar behavior. Here are my observations regarding the styles in wxFormBuilder:

By default, wxFormBuilder enables wxSP_3D. If you also check wxSP_NO_XP_THEME, the border style changes and the sash becomes visible. Based on this, I found that:

• If wxSP_3D is unchecked: Checking wxSP_3DBORDER or wxSP_BORDER only changes the border.
• If wxSP_3D is unchecked: Checking wxSP_3DSASH only makes the sash appear.

Conclusion:
It seems that wxSP_3D behaves as:
wxSP_3D = (wxSP_3DSASH | wxSP_3DBORDER) or (wxSP_3DSASH | wxSP_BORDER)

Workaround:
If you only want to display the sash, try enabling wxSP_NO_XP_THEME. This works successfully in both the wxFormBuilder preview (press F5 than OK) and the following code:

import wx

class MyFrame2(wx.Frame):
    def __init__(self, parent):
        wx.Frame.__init__(
            self,
            parent,
            id=wx.ID_ANY,
            title=wx.EmptyString,
            pos=wx.DefaultPosition,
            size=wx.Size(500, 300),
            style=wx.DEFAULT_FRAME_STYLE | wx.TAB_TRAVERSAL,
        )

        self.SetSizeHints(wx.DefaultSize, wx.DefaultSize)
        bSizer47 = wx.BoxSizer(wx.VERTICAL)

        # Applying wxSP_3DSASH | wxSP_NO_XP_THEME
        self.m_splitter4 = wx.SplitterWindow(
            self,
            wx.ID_ANY,
            wx.DefaultPosition,
            wx.DefaultSize,
            wx.SP_3DSASH | wx.SP_NO_XP_THEME,
        )
        self.m_splitter4.Bind(wx.EVT_IDLE, self.m_splitter4OnIdle)

        self.m_panel14 = wx.Panel(
            self.m_splitter4,
            wx.ID_ANY,
            wx.DefaultPosition,
            wx.DefaultSize,
            wx.TAB_TRAVERSAL,
        )
        self.m_panel15 = wx.Panel(
            self.m_splitter4,
            wx.ID_ANY,
            wx.DefaultPosition,
            wx.DefaultSize,
            wx.TAB_TRAVERSAL,
        )
        self.m_splitter4.SplitVertically(self.m_panel14, self.m_panel15, 200)
        bSizer47.Add(self.m_splitter4, 1, wx.EXPAND, 5)

        self.SetSizer(bSizer47)
        self.Layout()
        self.Centre(wx.BOTH)

    def m_splitter4OnIdle(self, event):
        self.m_splitter4.SetSashPosition(200)
        self.m_splitter4.Unbind(wx.EVT_IDLE)

if __name__ == "__main__":
    app = wx.App()
    frame = MyFrame2(None)
    frame.Show()
    app.MainLoop()

Result:

Side Note: I noticed that checking wxSP_THIN_SASH causes an error in the wxFormBuilder preview, but the code runs without issues in the actual application.