Function txt_selectable 

pub fn txt_selectable(
    child: impl IntoUiNode,
    enabled: impl IntoVar<bool>,
) -> UiNode

P Enable text selection, copy and makes the widget focusable.

Note that if the text widget subscribes to mouse or touch events the selection gestures will interfere with those events, you can enable txt_selectable_alt_only so that pointer selection gestures only start when the Alt keyboard modifier is pressed.

Sets the TEXT_SELECTABLE_VAR.