Decrease margins around the editor and project manager windows

This increases the screen real estate available for Godot, especially
at smaller window sizes.

The editor icons for tab options were resized from 6×16 to 16×16
so they don't touch the window edge. Incindentally, this also makes them
easier to click.

editor/editor_node.cpp

@@ -5933,8 +5933,12 @@ EditorNode::EditorNode() {
 
 	main_vbox = memnew(VBoxContainer);
 	gui_base->add_child(main_vbox);
-	main_vbox->set_anchors_and_offsets_preset(Control::PRESET_WIDE, Control::PRESET_MODE_MINSIZE, 8);
-	main_vbox->add_theme_constant_override("separation", 8 * EDSCALE);
+	// Add just one pixel of offset on all sides to prevent text or controls from touching the edges of the screen,
+	// and being partially occluded on some displays.
+	main_vbox->set_anchors_and_offsets_preset(Control::PRESET_WIDE, Control::PRESET_MODE_MINSIZE, Math::round(EDSCALE));
+	// Add some offset at the top to avoid making text touch the window's top edge.
+	main_vbox->set_offset(SIDE_TOP, Math::round(4 * EDSCALE));
+	main_vbox->add_theme_constant_override("separation", Math::round(4 * EDSCALE));
 
 	menu_hb = memnew(HBoxContainer);
 	main_vbox->add_child(menu_hb);

editor/project_manager.cpp

@@ -2472,7 +2472,11 @@ ProjectManager::ProjectManager() {
 
 	VBoxContainer *vb = memnew(VBoxContainer);
 	panel->add_child(vb);
-	vb->set_anchors_and_offsets_preset(Control::PRESET_WIDE, Control::PRESET_MODE_MINSIZE, 8 * EDSCALE);
+	// Add just one pixel of offset on all sides to prevent text or controls from touching the edges of the screen,
+	// and being partially occluded on some displays.
+	vb->set_anchors_and_offsets_preset(Control::PRESET_WIDE, Control::PRESET_MODE_MINSIZE, Math::round(EDSCALE));
+	// Add some offset at the top to avoid making text touch the window's top edge.
+	vb->set_offset(SIDE_TOP, Math::round(4 * EDSCALE));
 
 	Control *center_box = memnew(Control);
 	center_box->set_v_size_flags(Control::SIZE_EXPAND_FILL);