commit 08a0bf0285e8b91e02696e90f2cf087f7702fe91
Author: Bùi Thành Nhân <hi@imnhan.com>
Date:   Sun May 17 10:32:37 2020 +0700

    show waiting cursor when doing slow task

diff --git a/src/mcross/gui/controller.py b/src/mcross/gui/controller.py
index 03acb19..0e4bf45 100644
--- a/src/mcross/gui/controller.py
+++ b/src/mcross/gui/controller.py
@@ -1,3 +1,4 @@
+import traceback
 from ssl import SSLCertVerificationError
 from tkinter import TclError, Tk, messagebox
 
@@ -10,7 +11,7 @@
     get,
 )
 from .model import Model
-from .view import View
+from .view import WAITING_CURSOR, View
 
 
 class Controller:
@@ -26,7 +27,11 @@ def __init__(self):
         self.pending_coros = []
 
         def schedule_as_coro(func):
-            return lambda *args: self.pending_coros.append(curio.spawn(func, *args))
+            def do_schedule(*args):
+                task = curio.spawn(self.show_waiting_cursor_during_task(func, *args))
+                self.pending_coros.append(task)
+
+            return do_schedule
 
         self.view.go_callback = schedule_as_coro(self.go_callback)
         self.view.link_click_callback = schedule_as_coro(self.link_click_callback)
@@ -48,21 +53,34 @@ async def main():
                     for coroutine in self.pending_coros:
                         await coroutine
                     self.pending_coros = []
-                    await curio.sleep(0.05)
+                    await curio.sleep(0.05)  # 50ms
             except TclError as e:
                 if "application has been destroyed" not in str(e):
                     raise
 
         curio.run(main)
 
-    async def go_callback(self, url: str):
-        # TODO more visual indications
+    async def show_waiting_cursor_during_task(self, func, *args):
+        self.view.text.config(cursor=WAITING_CURSOR)
+        self.root.config(cursor=WAITING_CURSOR)
+        self.view.allow_changing_cursor = False
+
+        try:
+            await func(*args)
+        except Exception:
+            # a catch-all here so that our show_waiting...() coroutine can be yielded
+            traceback.print_exc()
+
+        # reset cursor to default values
+        self.view.text.config(cursor="xterm")
+        self.root.config(cursor="arrow")
+        self.view.allow_changing_cursor = True
 
+    async def go_callback(self, url: str):
         url = GeminiUrl.parse_absolute_url(url)
         await self.visit_link(url)
 
     async def link_click_callback(self, raw_url):
-        # FIXME ugh
         try:
             url = GeminiUrl.parse(raw_url, self.model.history.get_current_url())
             await self.visit_link(url)
@@ -97,9 +115,9 @@ async def forward_callback(self):
         self.view.render_page()
 
     async def load_page(self, url: GeminiUrl):
-        print("Requesting", url)
+        # print("Requesting", url)
         resp = await get(url)
-        print("Received", resp)
+        # print("Received", resp)
 
         if resp.status.startswith("2"):
             self.model.update_content(resp.body.decode())
diff --git a/src/mcross/gui/view.py b/src/mcross/gui/view.py
index 1b0f801..c8d5244 100644
--- a/src/mcross/gui/view.py
+++ b/src/mcross/gui/view.py
@@ -18,12 +18,15 @@
 if sys.platform == "win32":
     TTK_THEME = "vista"
     POINTER_CURSOR = "center_ptr"
+    WAITING_CURSOR = "wait"
 elif sys.platform == "darwin":
     TTK_THEME = "aqua"
     POINTER_CURSOR = "pointinghand"
+    WAITING_CURSOR = "wait"
 else:
     TTK_THEME = "clam"
     POINTER_CURSOR = "hand1"
+    WAITING_CURSOR = "watch"
 
 
 def pick_font(names):
@@ -49,6 +52,8 @@ class View:
     forward_btn: ttk.Button
     text: Text
 
+    allow_changing_cursor = True
+
     go_callback = None
     link_click_callback = None
     back_callback = None
@@ -153,10 +158,12 @@ def _on_go(self, ev=None):
             self.go_callback("gemini://" + self.address_bar.get())
 
     def _on_link_enter(self, ev):
-        self.text.config(cursor=POINTER_CURSOR)
+        if self.allow_changing_cursor:
+            self.text.config(cursor=POINTER_CURSOR)
 
     def _on_link_leave(self, ev):
-        self.text.config(cursor="xterm")
+        if self.allow_changing_cursor:
+            self.text.config(cursor="xterm")
 
     def _on_link_click(self, ev):
         raw_url = get_content_from_tag_click_event(ev)