[API] gtk_label_set_pattern does not work, the label cannot be set pattern

[yanglei]

Bug detailed description:
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GtkWidget * label=gtk_label_new("test);
gtk_label_set_pattern(GTK_LABEL(label), "____");

This should display a label with underlin text "test", but cannot see the underline in MID stack.

Reproduce steps:
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write app to show label

Current result:
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label text has no underline

Expected result:
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show label with underline text

Basic root-causing log:
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[Horace (horace-li)]

This is a GTK bug, that gtklabel didn't set pango attributes when calling gtk_label_set_pattern, only effective_attrs is set. To provide a workaround on adding underline to specified text string, please call gtk_label_set_attributes with customized PangoAttributes.

I would suggest this bug priority as low since we have an alternative way to add underline.