Resolves: tdf#122597 chart dialog should be modal

Change-Id: I66881168fe2c6f3d033f2037e3d1b884bb74bc1a
Reviewed-on: https://gerrit.libreoffice.org/66016
Tested-by: Jenkins
Reviewed-by: Adolfo Jayme Barrientos <fitojb@ubuntu.com>
diff --git a/chart2/uiconfig/ui/attributedialog.ui b/chart2/uiconfig/ui/attributedialog.ui
index bae0f3e..943d43a 100644
--- a/chart2/uiconfig/ui/attributedialog.ui
+++ b/chart2/uiconfig/ui/attributedialog.ui
@@ -5,6 +5,7 @@
  <object class="GtkDialog" id="AttributeDialog">
    <property name="can_focus">False</property>
    <property name="border_width">6</property>
    <property name="modal">True</property>
    <property name="default_width">0</property>
    <property name="default_height">0</property>
    <property name="type_hint">dialog</property>