Review of attachment 188967 [details] [review]:

::: gtk/gtkaccellabel.c
@@ +432,2 @@
       if (direction == GTK_TEXT_DIR_RTL)
+        x = (margin_left + margin_right) / 2;

This is not really the same thing, or is it ?
I would expect to use margin_left/_right here, as appropriate

::: gtk/gtkarrow.c
@@ +355,3 @@
 
+  x = (margin_left + margin_right) / 2 + ((width - extent) * xalign);
+  y = (margin_top + margin_bottom) / 2 + ((height - extent) * yalign);

Again here. Whats with all the averaging ?

::: gtk/gtklabel.c
@@ +3967,3 @@
   gtk_widget_get_allocation (widget, &allocation);
 
+  x = floor (allocation.x + (margin_right + margin_left) / 2 + xalign * (allocation.width - req_width) - logical.x);

Here too, I would expect to use either left or right as appropriate, not their average.

You cannot use gtk_widget_get_margin_*() APIs in draw, size_allocate or get_preferred_*() functions. They work completely different. Margins are taken care of automatically already.
That said, changing those functions would also stop gtk_misc_set_padding() from working, so it's an API break.

If we wanted to replace it like that, we should make gtk_misc_set_padding() call gtk_widget_set_margin() and replace all gtk_misc_get_padding() calls with 0.

Created attachment 189074 [details] [review]
Replace gtk_misc_set_padding() with GtkWidget:margin properties

After talking with Benjamin, seems that we cannot replace misc_get_padding() with widget_get_margin().
We can only replace misc_get_padding() with 0 - but that breaks anybody using misc_set_padding, so seems we can only remove the misc_set() calls

Apart from me wondering if we should have a gtk_widget_set_margin() shorthand and using that instead of g_object_set(), the patch looks fine.

Comment on attachment 189074 [details] [review]
Replace gtk_misc_set_padding() with GtkWidget:margin properties

commit 32ef28bc8592e0983c5b31ae64a30847164b981e

(In reply to comment #4)
> Apart from me wondering if we should have a gtk_widget_set_margin() shorthand
> and using that instead of g_object_set(), 

Filled bug #651720