Hi Frank,
The buttons for applying and clearing filters in the FilteringControl had fixed width which leads to their content being cut off in some cultures in the Windows8Touch theme. This fixed width is now removed and the FilteringControl's Width is now a fixed value that is updated for all themes - it is increased to display the full text when using the themes' default font size in combination with any of the available cultures.
Please, consider defining a Style targeting the FilteringControl which changes its width when applying different (more specifically bigger) font sizes.
The above described changes should be available with our next major release, scheduled for mid September.
Regards,
Vicky
Progress Telerik