fix build failure on Windows due to conflicting define with Win32 API

src/Gui/Quarter/InputDevice.cpp

@@ -48,7 +48,7 @@ using namespace SIM::Coin3D::Quarter;
   devices.
 */
 
-InputDevice::InputDevice(void)
+InputDevice::InputDevice(void) : quarter(nullptr)
 {
   this->mousepos = SbVec2s(0, 0);
 }

src/Gui/Quarter/Mouse.cpp

@@ -55,6 +55,9 @@
 #include <Inventor/SbVec2s.h>
 #include <Inventor/events/SoEvents.h>
 #include <Inventor/errors/SoDebugError.h>
+#if QT_VERSION >= 0x050000
+#include <Quarter/QuarterWidget.h>
+#endif
 
 namespace SIM { namespace Coin3D { namespace Quarter {
 

src/Gui/Quarter/QuarterWidget.cpp

@@ -835,7 +835,7 @@ void QuarterWidget::resizeEvent(QResizeEvent* event)
 */
 void QuarterWidget::paintEvent(QPaintEvent* event)
 {
-    if(updateDevicePixelRatio()) {
+    if (updateDevicePixelRatio()) {
         qreal dev_pix_ratio = devicePixelRatio();
         int width = static_cast<int>(dev_pix_ratio * this->width());
         int height = static_cast<int>(dev_pix_ratio * this->height());

src/Gui/Quarter/devices/InputDevice.h

@@ -35,7 +35,6 @@
 
 #include <Quarter/Basic.h>
 #include <Inventor/SbVec2s.h>
-#include <Quarter/QuarterWidget.h>
 
 class QEvent;
 class SoEvent;
@@ -43,6 +42,8 @@ class QInputEvent;
 
 namespace SIM { namespace Coin3D { namespace Quarter {
 
+class QuarterWidget;
+
 class QUARTER_DLL_API InputDevice {
 public:
   InputDevice(QuarterWidget * quarter);