python – 聚焦时不要设置Gtk.TreeView的选择？

以下代码显示一个带有按钮和树视图的窗口. “clicked”信号的句柄附加到按钮并聚焦树视图.最初显示窗口时,树选择没有选定的项目,但是当树视图获得焦点时,将自动选择第一个项目.有没有办法在树视图获得焦点时保持选择？

在单击之前,按钮具有焦点,树选择没有选定项目.单击后,树视图具有焦点,但已选择一个项目.

由此产生的问题是我有一个接口,通过附加到树视图的树选择上的“已更改”信号来保持一些事物同步.显示窗口时,根据树视图在界面中的位置,默认情况下它们可能会获得焦点.这会导致“已更改”信号,并发生意外同步.可以为所有树视图调用set_can_focus(False),但是：

>仅防止键盘循环焦点,而不是程序化焦点,选择仍然以程序焦点开启;和
>似乎禁用取消选择选择的功能(例如,通过按住控件单击某行).

类似地,我可以使用grab_default来确保在显示窗口时其他东西首先获得焦点,但是它不会使杂散焦点事件不能进行意外选择.

基于a posted answer表示选择模式SINGLE“需要至少选择一个项目”,并且这解释了为什么在焦点上选择了一个元素,我更多地考虑了选择模式常量.其中,SINGLE和BROWSE似乎最相关. pygtk文档,GTK Selection Mode Constants,只说：

gtk.SELECTION_SINGLE A single selection allowed by clicking.
gtk.SELECTION_BROWSE A single selection allowed by browsing with the pointer.

GTK 3文档enum GtkSelectionMode详细介绍了一些内容：

GTK_SELECTION_SINGLE Zero or one element may be selected.
GTK_SELECTION_BROWSE Exactly one element is selected. In some
circumstances,such as initially or during a search operation,it’s
possible for no element to be selected with GTK_SELECTION_BROWSE. What
is really enforced is that the user can’t deselect a currently
selected element except by selecting another element.

我在这里看不到任何暗示当选择模式为SINGLE时必须至少选择一个元素.

这是重现窗口的代码,并作为示例.

from gi.repository import Gtk

# A ListStore with some words
list_store = Gtk.ListStore(str)
for selection in "Can a machine think?".split():
    list_store.append([selection])

# A TreeView with a single column
tree_view = Gtk.TreeView(model=list_store)
cell_renderer = Gtk.CellRendererText()
tree_view_column = Gtk.TreeViewColumn(cell_renderer=cell_renderer,text=0,title='Words')
tree_view.append_column(tree_view_column)

# A button to focus the list
focus = Gtk.Button(label='Focus List')
focus.connect('clicked',lambda *_: tree_view.grab_focus())

# A Box to hold everything,and a Window for the Box.
box = Gtk.Box(orientation=Gtk.Orientation.VERTICAL)
box.add(focus)       # button on top gets initial focus
box.add(tree_view)   # tree_view below doesn't,and has no selected items 
window = Gtk.Window()
window.add(box)
window.show_all()

Gtk.main()

def tree_view_grab_focus():
    selection = tree_view.get_selection()
    _,selected = selection.get_selected()
    Gtk.TreeView.grab_focus(tree_view)
    if selected is None:
        selection.unselect_all()

tree_view.grab_focus = tree_view_grab_focus