Prevent panels from getting so small they can't be resized (#3788)

This also switches to using `Pixels` instead of `f32` to store the panel
size everywhere.

Release Notes:

- N/A

crates/collab_ui2/src/chat_panel.rs

@@ -51,7 +51,7 @@ pub struct ChatPanel {
     input_editor: View<MessageEditor>,
     local_timezone: UtcOffset,
     fs: Arc<dyn Fs>,
-    width: Option<f32>,
+    width: Option<Pixels>,
     active: bool,
     pending_serialization: Task<Option<()>>,
     subscriptions: Vec<gpui::Subscription>,
@@ -62,7 +62,7 @@ pub struct ChatPanel {
 
 #[derive(Serialize, Deserialize)]
 struct SerializedChatPanel {
-    width: Option<f32>,
+    width: Option<Pixels>,
 }
 
 #[derive(Debug)]
@@ -584,12 +584,12 @@ impl Panel for ChatPanel {
         });
     }
 
-    fn size(&self, cx: &gpui::WindowContext) -> f32 {
+    fn size(&self, cx: &gpui::WindowContext) -> Pixels {
         self.width
             .unwrap_or_else(|| ChatPanelSettings::get_global(cx).default_width)
     }
 
-    fn set_size(&mut self, size: Option<f32>, cx: &mut ViewContext<Self>) {
+    fn set_size(&mut self, size: Option<Pixels>, cx: &mut ViewContext<Self>) {
         self.width = size;
         self.serialize(cx);
         cx.notify();

crates/collab_ui2/src/collab_panel.rs

@@ -2314,15 +2314,13 @@ impl Panel for CollabPanel {
         );
     }
 
-    fn size(&self, cx: &gpui::WindowContext) -> f32 {
-        self.width.map_or_else(
-            || CollaborationPanelSettings::get_global(cx).default_width,
-            |width| width.0,
-        )
+    fn size(&self, cx: &gpui::WindowContext) -> Pixels {
+        self.width
+            .unwrap_or_else(|| CollaborationPanelSettings::get_global(cx).default_width)
     }
 
-    fn set_size(&mut self, size: Option<f32>, cx: &mut ViewContext<Self>) {
-        self.width = size.map(|s| px(s));
+    fn set_size(&mut self, size: Option<Pixels>, cx: &mut ViewContext<Self>) {
+        self.width = size;
         self.serialize(cx);
         cx.notify();
     }

crates/collab_ui2/src/notification_panel.rs

@@ -37,7 +37,7 @@ pub struct NotificationPanel {
     channel_store: Model<ChannelStore>,
     notification_store: Model<NotificationStore>,
     fs: Arc<dyn Fs>,
-    width: Option<f32>,
+    width: Option<Pixels>,
     active: bool,
     notification_list: ListState,
     pending_serialization: Task<Option<()>>,
@@ -51,7 +51,7 @@ pub struct NotificationPanel {
 
 #[derive(Serialize, Deserialize)]
 struct SerializedNotificationPanel {
-    width: Option<f32>,
+    width: Option<Pixels>,
 }
 
 #[derive(Debug)]
@@ -639,12 +639,12 @@ impl Panel for NotificationPanel {
         );
     }
 
-    fn size(&self, cx: &gpui::WindowContext) -> f32 {
+    fn size(&self, cx: &gpui::WindowContext) -> Pixels {
         self.width
             .unwrap_or_else(|| NotificationPanelSettings::get_global(cx).default_width)
     }
 
-    fn set_size(&mut self, size: Option<f32>, cx: &mut ViewContext<Self>) {
+    fn set_size(&mut self, size: Option<Pixels>, cx: &mut ViewContext<Self>) {
         self.width = size;
         self.serialize(cx);
         cx.notify();

crates/collab_ui2/src/panel_settings.rs

@@ -1,4 +1,5 @@
 use anyhow;
+use gpui::Pixels;
 use schemars::JsonSchema;
 use serde_derive::{Deserialize, Serialize};
 use settings::Settings;
@@ -8,21 +9,21 @@ use workspace::dock::DockPosition;
 pub struct CollaborationPanelSettings {
     pub button: bool,
     pub dock: DockPosition,
-    pub default_width: f32,
+    pub default_width: Pixels,
 }
 
 #[derive(Deserialize, Debug)]
 pub struct ChatPanelSettings {
     pub button: bool,
     pub dock: DockPosition,
-    pub default_width: f32,
+    pub default_width: Pixels,
 }
 
 #[derive(Deserialize, Debug)]
 pub struct NotificationPanelSettings {
     pub button: bool,
     pub dock: DockPosition,
-    pub default_width: f32,
+    pub default_width: Pixels,
 }
 
 #[derive(Clone, Default, Serialize, Deserialize, JsonSchema, Debug)]