private void markButton(final CharButton newButton) {
        final CharButton prevButton = this.markedButton;
        this.markedButton = null;

        if (prevButton != null) {
            prevButton.unmark();
        }

        if (newButton != null) {
            newButton.mark();
            this.valueLayout.setVisibility(VISIBLE);
            this.valueHiddenHint.setVisibility(INVISIBLE);
            this.value.setText(newButton.getText());
            this.value.requestFocus();
            this.value.setSelection(0, newButton.getText().length());
            Keyboard.show(getContext(), this.value);
        } else {
            this.value.setText("");
            this.valueLayout.setVisibility(INVISIBLE);
            this.valueHiddenHint.setVisibility(VISIBLE);
        }

        this.markedButton = newButton;
    }
returns true if latPatternn/lonPattern could be applied, false otherwise
main/src/main/java/cgeo/geocaching/ui/CalculatedCoordinateInputGuideView.java