use group(?)-agnostic keyval for paste shortcut (fixes #228)

src/misc/events.cpp

@@ -0,0 +1,15 @@
+#include "events.hpp"
+
+namespace EventsUtil {
+unsigned shortcut_key(GdkEventKey *event) {
+    // thanks inkscape
+    unsigned shortcut_key = 0;
+    gdk_keymap_translate_keyboard_state(
+        gdk_keymap_get_for_display(gdk_display_get_default()),
+        event->hardware_keycode,
+        static_cast<GdkModifierType>(event->state),
+        0,
+        &shortcut_key, nullptr, nullptr, nullptr);
+    return shortcut_key;
+}
+} // namespace EventsUtil

src/misc/events.hpp

@@ -0,0 +1,7 @@
+#pragma once
+#include <gdk/gdkkeys.h>
+// idk it wont let me forward declare
+
+namespace EventsUtil {
+unsigned shortcut_key(GdkEventKey *event);
+}