diff --git a/Xlib/XK.py b/Xlib/XK.py
index 7603ccd..4749b54 100644
--- a/Xlib/XK.py
+++ b/Xlib/XK.py
@@ -24,6 +24,10 @@
 # definition modules in the Xlib/keysymdef directory.
 
 from Xlib.X import NoSymbol
+try:
+    from typing import TYPE_CHECKING
+except ImportError:
+    TYPE_CHECKING = False
 
 def string_to_keysym(keysym):
     '''Return the (16 bit) numeric code of keysym.
@@ -64,7 +68,11 @@ def _load_keysyms_into_XK(mod):
 
 # Always import miscellany and latin1 keysyms
 load_keysym_group('miscellany')
+if TYPE_CHECKING:
+    from Xlib.keysymdef.miscellany import *
 load_keysym_group('latin1')
+if TYPE_CHECKING:
+    from Xlib.keysymdef.latin1 import *
 
 
 def keysym_to_string(keysym):
diff --git a/Xlib/ext/xinput.py b/Xlib/ext/xinput.py
index f921806..1ad98d4 100644
--- a/Xlib/ext/xinput.py
+++ b/Xlib/ext/xinput.py
@@ -226,8 +226,9 @@ def pack_value(self, val):
             # bytes we build a longer array, being careful to maintain native
             # byte order across the entire set of values.
             if sys.byteorder == 'little':
-                def fun(val):
-                    mask_seq.insert(0, val)
+                def fun(__v):
+                    # type: (int) -> None
+                    mask_seq.insert(0, __v)
             elif sys.byteorder == 'big':
                 fun = mask_seq.append
             else:
@@ -308,6 +309,8 @@ def __init__(self, name):
         rq.ValueField.__init__(self, name)
 
     def parse_binary_value(self, data, display, length, fmt):
+        if length is None:
+            length = len(data)
         # Mask: bitfield of <length> button states.
         mask_len = 4 * ((((length + 7) >> 3) + 3) >> 2)
         mask_data = data[:mask_len]
@@ -378,7 +381,7 @@ def parse_binary_value(self, data, display, length, fmt):
 }
 
 class ClassInfoClass(object):
-
+    check_value = None
     structcode = None
 
     def parse_binary(self, data, display):
diff --git a/Xlib/protocol/display.py b/Xlib/protocol/display.py
index 0d910da..a872f83 100644
--- a/Xlib/protocol/display.py
+++ b/Xlib/protocol/display.py
@@ -79,6 +79,7 @@ class Display(object):
     extension_major_opcodes = {}
     error_classes = error.xerror_class.copy()
     event_classes = event.event_class.copy()
+    resource_classes = {}  # type: _BaseClasses
 
     def __init__(self, display = None):
         name, protocol, host, displayno, screenno = connect.get_display(display)
@@ -360,20 +361,20 @@ def send_request(self, request, wait_for_response):
         self.request_serial = (self.request_serial + 1) % 65536
 
         self.request_queue.append((request, wait_for_response))
-        qlen = len(self.request_queue)
+        # qlen = len(self.request_queue)
 
         self.request_queue_lock.release()
 
-#       if qlen > 10:
-#           self.flush()
+        # if qlen > 10:
+        #     self.flush()
 
     def close_internal(self, whom):
         # Clear out data structures
-        self.request_queue = None
-        self.sent_requests = None
-        self.event_queue = None
-        self.data_send = None
-        self.data_recv = None
+        self.request_queue = []
+        self.sent_requests = []
+        self.event_queue = []
+        self.data_send = b''
+        self.data_recv = b''
 
         # Close the connection
         self.socket.close()
@@ -583,7 +584,7 @@ def send_and_recv(self, flush = False, event = False, request = None, recv = Fal
                     i = self.socket.send(self.data_send)
                 except socket.error as err:
                     self.close_internal('server: %s' % err)
-                    raise self.socket_error
+                    raise self.socket_error or Exception()
 
                 self.data_send = self.data_send[i:]
                 self.data_sent_bytes = self.data_sent_bytes + i
@@ -601,12 +602,12 @@ def send_and_recv(self, flush = False, event = False, request = None, recv = Fal
                         bytes_recv = self.socket.recv(count)
                     except socket.error as err:
                         self.close_internal('server: %s' % err)
-                        raise self.socket_error
+                        raise self.socket_error or Exception()
 
                     if not bytes_recv:
                         # Clear up, set a connection closed indicator and raise it
                         self.close_internal('server')
-                        raise self.socket_error
+                        raise self.socket_error or Exception()
 
                     self.data_recv = bytes(self.data_recv) + bytes_recv
                     gotreq = self.parse_response(request)
@@ -690,6 +691,7 @@ def parse_response(self, request):
 
         # Parse ordinary server response
         gotreq = False
+        rtype = None
         while True:
             if self.data_recv:
                 # Check the first byte to find out what kind of response it is
@@ -703,7 +705,7 @@ def parse_response(self, request):
                 if rtype == 1:
                     gotreq = self.parse_request_response(request) or gotreq
                     continue
-                elif rtype & 0x7f == ge.GenericEventCode:
+                elif rtype and (rtype & 0x7f == ge.GenericEventCode):
                     self.parse_event_response(rtype)
                     continue
                 else:
@@ -711,7 +713,7 @@ def parse_response(self, request):
 
             # Every response is at least 32 bytes long, so don't bother
             # until we have received that much
-            if len(self.data_recv) < 32:
+            if len(self.data_recv) < 32 or rtype is None:
                 return gotreq
 
             # Error response
@@ -719,7 +721,7 @@ def parse_response(self, request):
                 gotreq = self.parse_error_response(request) or gotreq
 
             # Request response or generic event.
-            elif rtype == 1 or rtype & 0x7f == ge.GenericEventCode:
+            elif rtype == 1 or (rtype & 0x7f == ge.GenericEventCode):
                 # Set reply length, and loop around to see if
                 # we have got the full response
                 rlen = int(struct.unpack('=L', self.data_recv[4:8])[0])
@@ -812,9 +814,10 @@ def parse_request_response(self, request):
 
     def parse_event_response(self, etype):
         # Skip bit 8, that is set if this event came from an SendEvent
-        etype = etype & 0x7f
+        etype = etype and (etype & 0x7f)
+        is_generic_event_code = etype == ge.GenericEventCode
 
-        if etype == ge.GenericEventCode:
+        if is_generic_event_code:
             length = self.recv_packet_len
         else:
             length = 32
@@ -832,7 +835,7 @@ def parse_event_response(self, etype):
 
         e = estruct(display = self, binarydata = self.data_recv[:length])
 
-        if etype == ge.GenericEventCode:
+        if is_generic_event_code:
             self.recv_packet_len = 0
 
         self.data_recv = bytesview(self.data_recv, length)
@@ -1022,6 +1025,7 @@ def parse_connection_setup(self):
 
 
 class ConnectionSetupRequest(rq.GetAttrData):
+    _serial = None  # type: int | None
     _request = rq.Struct( rq.Set('byte_order', 1, (0x42, 0x6c)),
                           rq.Pad(1),
                           rq.Card16('protocol_major'),
@@ -1061,7 +1065,7 @@ class ConnectionSetupRequest(rq.GetAttrData):
 
     def __init__(self, display, *args, **keys):
         self._binary = self._request.to_binary(*args, **keys)
-        self._data = None
+        self._data = {}  # type: dict[str, object]
 
         # Don't bother about locking, since no other threads have
         # access to the display yet
diff --git a/Xlib/protocol/rq.py b/Xlib/protocol/rq.py
index 8bc8205..80a75a8 100644
--- a/Xlib/protocol/rq.py
+++ b/Xlib/protocol/rq.py
@@ -109,8 +109,9 @@ class Field(object):
     f.parse_binary_value() instead.  See its documentation string for
     details.
     """
-    name = None
+    name = ""
     default = None
+    pack_value = None  # type: Callable[[Any], tuple[Any, int | None, int | None]] | None
 
     structcode = None
     structvalues = 0
@@ -184,6 +185,10 @@ class LengthField(Field):
     structvalues = 1
     other_fields = None
 
+    def parse_binary_value(self, data = None, display = None, length = None, format = None):
+        # type: (object, object, object, object) -> tuple[Any, _SliceableBuffer]
+        return b'', b''
+
     def calc_length(self, length):
         """newlen = lf.calc_length(length)
 
@@ -301,8 +306,8 @@ def check_value(self, value):
             return value
 
     def parse_value(self, value, display):
-        # if not display:
-        #    return value
+        if not display:
+           return value
         if value in self.codes:
             return value
 
@@ -468,7 +473,9 @@ def pack_value(self, val):
         return struct.pack('>' + 'H' * slen, *val) + pad, slen, None
 
     def parse_binary_value(self, data, display, length, format):
-        if length == 'odd':
+        if length is None:
+            length = len(data)
+        elif length == 'odd':
             length = len(data) // 2 - 1
         elif length == 'even':
             length = len(data) // 2
@@ -653,10 +660,9 @@ def parse_binary_value(self, data, display, length, format):
         else:
             length = int(length)
 
-        if format == 0:
-            ret = None
+        ret = None
 
-        elif format == 8:
+        if format == 8:
             ret = (8, data[:length])
             data = data[length + ((4 - length % 4) % 4):]
 
@@ -892,8 +898,8 @@ def __init__(self, class_name):
         self.check_value = None
 
     def parse_value(self, value, display):
-        # if not display:
-        #     return value
+        if not display:
+            return value
         c = display.get_resource_class(self.class_name)
         if c:
             return c(display, value)
@@ -937,6 +943,9 @@ class Field.  The fields of a structure are given as arguments
     object to make conversion as fast as possible.  They are
     generated the first time the methods are called.
     """
+    name = ""
+    check_value = None  # type: Callable[[Any], Any] | None
+    keyword_args = False
 
     def __init__(self, *fields):
         self.fields = fields
@@ -1014,6 +1023,9 @@ def to_binary(self, *varargs, **keys):
         formats = {}
 
         for f in self.var_fields:
+            if not f.pack_value:
+                continue
+
             if f.keyword_args:
                 v, l, fm = f.pack_value(field_args[f.name], keys)
             else:
@@ -1287,13 +1299,13 @@ class TextElements16(TextElements8):
 
 
 class GetAttrData(object):
+    _data = {} # type: dict[str, object]
+    # GetAttrData classes get their attributes dynamically
+    # TODO: Complete all classes inheriting from GetAttrData
     def __getattr__(self, attr):
         try:
-            if self._data:
-                return self._data[attr]
-            else:
-                raise AttributeError(attr)
-        except KeyError:
+            return self._data[attr]
+        except (KeyError, AttributeError):
             raise AttributeError(attr)
 
 class DictWrapper(GetAttrData):
@@ -1341,6 +1353,7 @@ def __eq__(self, other):
 
 
 class Request(object):
+    _request = None  # type: Struct
     def __init__(self, display, onerror = None, *args, **keys):
         self._errorhandler = onerror
         self._binary = self._request.to_binary(*args, **keys)
@@ -1354,11 +1367,11 @@ def _set_error(self, error):
             return 0
 
 class ReplyRequest(GetAttrData):
+    _request = None  # type: Struct
     def __init__(self, display, defer = False, *args, **keys):
         self._display = display
         self._binary = self._request.to_binary(*args, **keys)
         self._serial = None
-        self._data = None
         self._error = None
 
         self._response_lock = lock.allocate_lock()
@@ -1371,9 +1384,11 @@ def reply(self):
         # Send request and wait for reply if we hasn't
         # already got one.  This means that reply() can safely
         # be called more than one time.
+        if self._display is None:
+            raise TypeError
 
         self._response_lock.acquire()
-        while self._data is None and self._error is None:
+        while not self._data and self._error is None:
             self._display.send_recv_lock.acquire()
             self._response_lock.release()
 
@@ -1403,6 +1418,7 @@ def __repr__(self):
 
 
 class Event(GetAttrData):
+    _fields = None # type: Struct
     def __init__(self, binarydata = None, display = None,
                  **keys):
         if binarydata:
diff --git a/Xlib/xobject/colormap.py b/Xlib/xobject/colormap.py
index 033fb49..a1508d9 100644
--- a/Xlib/xobject/colormap.py
+++ b/Xlib/xobject/colormap.py
@@ -44,7 +44,7 @@ def free(self, onerror = None):
 
         self.display.free_resource_id(self.id)
 
-    def copy_colormap_and_free(self, scr_cmap):
+    def copy_colormap_and_free(self, src_cmap):
         mid = self.display.allocate_resource_id()
         request.CopyColormapAndFree(display = self.display,
                                     mid = mid,