T30: the main window opens at the size it was left at: its size, read once the bounds settle and kept in the settings unless the window is maximized or full screen, opens the next window, shrunk where it passes the screen

src/settings/mod.rs

@@ -75,6 +75,9 @@ pub struct Settings {
     pub show_sessions: bool,
     pub show_panel: bool,
     pub panel: PanelTab,
+    /// The main window's size, unmaximized, in pixels.
+    pub window_width: f32,
+    pub window_height: f32,
 }
 
 impl Default for Settings {
@@ -100,6 +103,8 @@ impl Default for Settings {
             show_sessions: true,
             show_panel: true,
             panel: PanelTab::Git,
+            window_width: 1200.0,
+            window_height: 760.0,
         }
     }
 }
@@ -109,6 +114,7 @@ pub const LINE_HEIGHT: RangeInclusive<f32> = 1.0..=2.0;
 pub const OPACITY: RangeInclusive<f32> = 0.3..=1.0;
 pub const PADDING: RangeInclusive<f32> = 0.0..=64.0;
 pub const SCROLLBACK: RangeInclusive<u32> = 0..=100_000;
+pub const WINDOW: RangeInclusive<f32> = 100.0..=16384.0;
 
 impl Settings {
     /// Every value inside its range, every theme built in; the error names the field.
@@ -119,6 +125,8 @@ impl Settings {
         within("padding_x", self.padding_x, &PADDING)?;
         within("padding_y", self.padding_y, &PADDING)?;
         within("scrollback", self.scrollback, &SCROLLBACK)?;
+        within("window_width", self.window_width, &WINDOW)?;
+        within("window_height", self.window_height, &WINDOW)?;
         for (field, id) in [
             ("theme", Some(&self.theme)),
             ("dark_theme", self.dark_theme.as_ref()),
@@ -225,6 +233,15 @@ mod tests {
             error.to_string(),
             "scrollback is 100001, outside 0 to 100000"
         );
+        let settings = Settings {
+            window_width: 50.0,
+            ..Settings::default()
+        };
+        let error = settings.validate().expect_err("too narrow");
+        assert_eq!(
+            error.to_string(),
+            "window_width is 50, outside 100 to 16384"
+        );
     }
 
     #[test]