[meld/ui-next] ui.statusbar: Set a reasonable cursor label width

[Kai Willadsen <kaiw src gnome org>]

commit 1917b750876421c3147f8544f6fb89db99a4a5e3
Author: Kai Willadsen <kai willadsen gmail com>
Date:   Sun Mar 24 09:55:41 2019 +1000

    ui.statusbar: Set a reasonable cursor label width
    
    The initial cursor label allocation is almost always enough to hold a
    couple of digits for line and a single digit for column... that's just
    where we expect initial cursors to end up. Having the allocation change
    when the cursor moves makes the statusbar feel dodgy, and it's frankly
    much nicer if all of the widgets stay in a constant place.
    
    The calculation here is a trade-off between line count + length that we
    expect users might hit vs. not wanting too much blank space between
    the cursor button and other statusbar widgets. The calculation is
    essentially the formatted version of having <10000 lines at <1000
    characters long... and the -2 is from practical testing, since the
    allocated space _easily_ fits more than the desired line counts with
    normal system fonts.

 meld/ui/statusbar.py | 7 +++++++
 1 file changed, 7 insertions(+)
---
diff --git a/meld/ui/statusbar.py b/meld/ui/statusbar.py
index 8a0062af..f00a30bb 100644
--- a/meld/ui/statusbar.py
+++ b/meld/ui/statusbar.py
@@ -72,6 +72,7 @@ class MeldStatusMenuButton(Gtk.MenuButton):
         label.props.single_line_mode = True
         label.props.halign = Gtk.Align.START
         label.props.valign = Gtk.Align.BASELINE
+        label.props.xalign = 1.0
 
         arrow = Gtk.Image.new_from_icon_name(
             'pan-down-symbolic', Gtk.IconSize.SMALL_TOOLBAR)
@@ -88,6 +89,9 @@ class MeldStatusMenuButton(Gtk.MenuButton):
 
         self._label = label
 
+    def set_label_width(self, width):
+        self._label.set_width_chars(width)
+
 
 class MeldStatusBar(Gtk.Statusbar):
     __gtype_name__ = "MeldStatusBar"
@@ -209,6 +213,9 @@ class MeldStatusBar(Gtk.Statusbar):
             format_cursor_position)
         self.connect('start-go-to-line', lambda *args: button.clicked())
         button.set_popover(pop)
+        # Set a label width to avoid other widgets moving on cursor change
+        reasonable_width = len(format_cursor_position(None, (1000, 100))) - 2
+        button.set_label_width(reasonable_width)
         button.show()
 
         return button