Add miscellaneous missing WinAPI functions, constants, and structures for comctl32, user32, and ux_theme.

core/sys/windows/comctl32.odin

@@ -5,6 +5,30 @@ foreign import "system:Comctl32.lib"
 
 @(default_calling_convention="system")
 foreign Comctl32 {
+	InitCommonControlsEx :: proc(picce: ^INITCOMMONCONTROLSEX) -> BOOL ---
 	LoadIconWithScaleDown :: proc(hinst: HINSTANCE, pszName: PCWSTR, cx: c_int, cy: c_int, phico: ^HICON) -> HRESULT ---
 	SetWindowSubclass :: proc(hwnd: HWND, pfnSubclass: SUBCLASSPROC, uIdSubclass: UINT_PTR, dwRefData: DWORD_PTR) ---
 }
+
+ICC_LISTVIEW_CLASSES   :: 0x00000001
+ICC_TREEVIEW_CLASSES   :: 0x00000002
+ICC_BAR_CLASSES        :: 0x00000004
+ICC_TAB_CLASSES        :: 0x00000008
+ICC_UPDOWN_CLASS       :: 0x00000010
+ICC_PROGRESS_CLASS     :: 0x00000020
+ICC_HOTKEY_CLASS       :: 0x00000040
+ICC_ANIMATE_CLASS      :: 0x00000080
+ICC_WIN95_CLASSES      :: 0x000000FF
+ICC_DATE_CLASSES       :: 0x00000100
+ICC_USEREX_CLASSES     :: 0x00000200
+ICC_COOL_CLASSES       :: 0x00000400
+ICC_INTERNET_CLASSES   :: 0x00000800
+ICC_PAGESCROLLER_CLASS :: 0x00001000
+ICC_NATIVEFNTCTL_CLASS :: 0x00002000
+ICC_STANDARD_CLASSES   :: 0x00004000
+ICC_LINK_CLASS         :: 0x00008000
+
+INITCOMMONCONTROLSEX :: struct {
+	dwSize: DWORD,
+	dwICC: DWORD,
+}