add horizontal center for colorpicker buttons

scene/gui/color_picker.cpp

@@ -1850,6 +1850,7 @@ ColorPicker::ColorPicker() {
 	real_vbox->add_child(sample_hbc);
 
 	btn_pick = memnew(Button);
+	btn_pick->set_icon_alignment(HORIZONTAL_ALIGNMENT_CENTER);
 	sample_hbc->add_child(btn_pick);
 
 	sample = memnew(TextureRect);
@@ -1863,6 +1864,7 @@ ColorPicker::ColorPicker() {
 	sample_hbc->add_child(btn_shape);
 	btn_shape->set_toggle_mode(true);
 	btn_shape->set_tooltip_text(ETR("Select a picker shape."));
+	btn_shape->set_icon_alignment(HORIZONTAL_ALIGNMENT_CENTER);
 
 	current_shape = SHAPE_HSV_RECTANGLE;