correct control overlapping - minor UI refactoring
correct control overlapping - minor UI refactoring

the gtk-cancel button overlapped the "adding extension" label if %EXTENSION_NAME is too long.

Change-Id: Ia6a650d7ff82853155da67527a1cdc865b01148e
Reviewed-on: https://gerrit.libreoffice.org/14717
Reviewed-by: Adolfo Jayme Barrientos <978aef1383ff7c89a424f1d44ea77bde9ab919ad@ubuntu.com>
Tested-by: Adolfo Jayme Barrientos <978aef1383ff7c89a424f1d44ea77bde9ab919ad@ubuntu.com>

JurassicWordExcel/core,JurassicWordExcel/core,JurassicWordExcel/core,JurassicWordExcel/core,JurassicWordExcel/core,JurassicWordExcel/core,JurassicWordExcel/core,JurassicWordExcel/core,JurassicWordExcel/core,JurassicWordExcel/core