ui: Fix total width of columns and add padding for wide terminals.

This commit adds Padding around a fixed total width of 200 of the
columns by centering it for wide terminals. The side columns also
expand from their min width until they occupy 200 columns in the
ratio 20:60:20.

Author: Rohitth007

zulipterminal/ui.py

@@ -32,6 +32,7 @@ class View(urwid.WidgetWrap):
 
     LEFT_WIDTH = 27
     RIGHT_WIDTH = 23
+    MAX_TOTAL_WIDTH = 200
 
     def __init__(self, controller: Any) -> None:
         self.controller = controller
@@ -142,16 +143,19 @@ def main_window(self) -> Any:
         if self.autohide:
             body = [
                 (self.LEFT_WIDTH, self.left_panel),
-                ("weight", 10, self.center_panel),
+                ("weight", 80, self.center_panel),
                 (0, self.right_panel),
             ]
         else:
             body = [
                 (self.LEFT_WIDTH, self.left_panel),
-                ("weight", 10, self.center_panel),
+                ("weight", 60, self.center_panel),
                 (self.RIGHT_WIDTH, self.right_panel),
             ]
         self.body = urwid.Columns(body, focus_column=0)
+        padded_body = urwid.Padding(
+            self.body, align="center", width=self.MAX_TOTAL_WIDTH
+        )
 
         # NOTE: message_view is None, but middle_column_view is called above
         # and sets it.
@@ -177,22 +181,36 @@ def main_window(self) -> Any:
         )
 
         w = urwid.Frame(
-            self.body, title_bar, focus_part="body", footer=self.footer_view()
+            padded_body, title_bar, focus_part="body", footer=self.footer_view()
         )
         return w
 
     def show_left_panel(self, *, visible: bool, ignore_check: bool = False) -> None:
         if not self.autohide and self.mode != "small" and not ignore_check:
             return
-        option = ("given", self.LEFT_WIDTH) if visible else ("given", 0)
+
+        if visible and self.mode != "wide":
+            option = ("given", self.LEFT_WIDTH)
+        elif visible and self.mode == "wide":
+            option = ("weight", 20)
+        else:
+            option = ("given", 0)
+
         self.body.contents[0] = (self.left_panel, self.body.options(*option))
         if visible:
             self.body.focus_position = 0
 
     def show_right_panel(self, *, visible: bool, ignore_check: bool = False) -> None:
         if not self.autohide and self.mode != "small" and not ignore_check:
             return
-        option = ("given", self.RIGHT_WIDTH) if visible else ("given", 0)
+
+        if visible and self.mode != "wide":
+            option = ("given", self.RIGHT_WIDTH)
+        elif visible and self.mode == "wide":
+            option = ("weight", 20)
+        else:
+            option = ("given", 0)
+
         self.body.contents[2] = (self.right_panel, self.body.options(*option))
         if visible:
             self.body.focus_position = 2
@@ -336,6 +354,23 @@ def render(self, size: urwid_Box, focus: bool) -> Any:
                 self.show_left_panel(visible=True, ignore_check=True)
                 self.body.focus_position = prev_focus
 
+        def update_column_options() -> None:
+            if not self.autohide:
+                self.show_left_panel(visible=True, ignore_check=True)
+                self.show_right_panel(visible=True, ignore_check=True)
+            if self.autohide:
+                if self.focus_col == 0:
+                    self.show_left_panel(visible=True)
+                elif self.focus_col == 2:
+                    self.show_right_panel(visible=True)
+
+        if maxcols > 160 and not self.mode == "wide":
+            self.mode = "wide"
+            update_column_options()
+        elif maxcols < 160 and self.mode == "wide":
+            self.mode = "normal"
+            update_column_options()
+
         return super().render(size, focus)