How to disable manual resizing of Tkinter's Treeview column?

Question

Since I can't horizontally scroll Treeview column due to what appears to be Tk/Tkinter limitation, I want to make it sticky so it is attached to the frame.

The issue is that user can manually resize Treeview column which can mess up my interface in a certain way. Is it possible to disable such functionality?

Note the size of the column header.

User can drag mouse to resize column. I want to disable this.

Setting minwidth to a certain value prevents column from shrinking, but it is still possible to resize it to a larger width. I suppose I can react to changing width and just revert it to original, but there has to be a better way to do it.

Answer 1

The following has only been tested on Windows, other OS's may vary.

For any future readers, since Tk 8.5, Treeviews have an identify_region method that accepts a screen position (x,y) and will return a string corresponding to the region of the treeview those coordinates occupy.

One of the return values is "separator".

I've used this to catch double-click events on the separator to auto-size columns, but you could also use it to catch single-click events and block them.

For example:

def handle_click(event):
    if treeview.identify_region(event.x, event.y) == "separator":
        return "break"

#...

treeview.bind('<Button-1>', handle_click)

This has the advantage of not rendering the entire treeview disabled -- so you can still select/expand/collapse rows, click column headings to sort, etc -- you just won't be able to resize the columns.

Note that even though resizing is disabled, the "double arrow" cursor (⇔) will still appear. You could additionally prevent the double arrow cursor from showing by doing the exact same thing with the <Motion> event (binding to it, checking if it's above a separator, and stopping the event from being propagated by returning the string "break").

>>> sys.version
'3.6.0 (v3.6.0:41df79263a11, Dec 23 2016, 08:06:12) [MSC v.1900 64 bit (AMD64)]'
>>> tkinter.TkVersion
8.6

Answer 2

I just found a decent solution. You can capture the mouse click before it reaches the widget, preventing the user to modify the column width.

def disableEvent(event):
    return "break"

treeviewName.bind("<Button-1>", disableEvent)

In case you need to really check which widget was pressed the event.widget contains the widget that was pressed.