How Can I Ensure My Custom Tkinter Text Widget Bindings Execute After Built-in Bindings?

Binding Custom Events in Tkinter Text Widget after Built-in Bindings

Understanding the Issue

In Tkinter's Text widget, you may encounter a situation where your custom event bindings are being executed before the widget's built-in bindings, causing discrepancies in text updates.

Solution

To address this issue, you can alter the order in which events are processed. Tkinter widgets are assigned a hierarchy of "bindtags" that determine the order of binding execution.

1. Rearranging Bindtags

The default order of bindtags is: widget, class, toplevel, all. You can change the order by placing the widget bindtag after the class bindtag. This way, class bindings will execute before widget bindings.

<code class="python"># Modify the bindtags to rearrange the order
entry.bindtags(('Entry', '.entry', '.', 'all'))</code>

2. Introducing Additional Bindtags

Alternatively, you can create a new bindtag after the class bindtag and bind your custom events to this new tag.

<code class="python"># Create a new bindtag "post-class-bindings" after the class bindtag
entry.bindtags(('.entry','Entry','post-class-bindings', '.', 'all'))

# Bind your custom events to "post-class-bindings"
entry.bind_class("post-class-bindings", "<KeyPress>", OnKeyPress)</code>

Benefits of Both Approaches

• Rearranging Bindtags: Affects all bindings on the widget.
• Introducing New Bindtags: Allows selective binding of events based on the bindtag order.

Example Code

The following code demonstrates both approaches:

<code class="python">import Tkinter

def OnKeyPress(event):
    value = event.widget.get()
    string="value of %s is '%s'" % (event.widget._name, value)
    status.configure(text=string)

root = Tkinter.Tk()

entry1 = Tkinter.Entry(root, name="entry1")
entry2 = Tkinter.Entry(root, name="entry2")
entry3 = Tkinter.Entry(root, name="entry3")

# Three different bindtags
entry1.bindtags(('.entry1', 'Entry', '.', 'all'))
entry2.bindtags(('Entry', '.entry2', '.', 'all'))
entry3.bindtags(('.entry3','Entry','post-class-bindings', '.', 'all'))

# Bind the first two entries to the default bind tags
entry1.bind("<KeyPress>", OnKeyPress)
entry2.bind("<KeyPress>", OnKeyPress)

# Bind the third entry to the "post-class-bindings" bind tag
entry3.bind_class("post-class-bindings", "<KeyPress>", OnKeyPress)

# ... Continue with your GUI code
</code>

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