How to make TreeViewItem ignore the arrow keys while

[robkri]

When I put a TextBox as content of a TreeViewItem, it seems like I cannot use the arrow keys to move the cursor inside the TextBox without triggering the short cuts of TreeViewItem. In the screencapture it can be seen, that instead of moving the cursor left, the item collapses when the left arrow key is pressed. Pressing it again makes the focus jump to the parent of "Item 2.3", making the TextBox lose its focus entirely:

Weirdly, the up and down arrow don't trigger TreeViewItem's short cuts but can be used to move the curser inside the TextBox.

Is there something I can do, to make TreeViewItem ignore the left and right arrow keys as long as the TextBox has focus so that I can use them to move the cursor?