Initialize all members and use nullptr instead of 0.

src/modules/keyboard/keyboardwidget/keyboardpreview.cpp

@@ -22,8 +22,11 @@
 
 #include "keyboardpreview.h"
 
-KeyBoardPreview::KeyBoardPreview(QWidget* parent) :
-    QWidget(parent)
+KeyBoardPreview::KeyBoardPreview( QWidget* parent )
+    : QWidget( parent )
+    , space( 0 )
+    , usable_width( 0 )
+    , key_w( 0 )
 {
     setMinimumSize(700, 191);
 

src/modules/keyboard/keyboardwidget/keyboardpreview.h

@@ -40,7 +40,7 @@ class KeyBoardPreview : public QWidget
 {
     Q_OBJECT
 public:
-    explicit KeyBoardPreview(QWidget* parent = 0);
+    explicit KeyBoardPreview( QWidget* parent = nullptr );
     
     void setLayout(QString layout);
     void setVariant(QString variant);