Omit GThreadLock and use IdleRegister in WhiteBalance (fixes #4545)

rtgui/whitebalance.cc

@@ -349,6 +349,10 @@ WhiteBalance::WhiteBalance () : FoldableToolPanel(this, "whitebalance", M("TP_WB
     spotsize->signal_changed().connect( sigc::mem_fun(*this, &WhiteBalance::spotSizeChanged) );
 }
 
+WhiteBalance::~WhiteBalance()
+{
+    idle_register.destroy();
+}
 
 void WhiteBalance::enabledChanged()
 {
@@ -895,12 +899,28 @@ inline Gtk::TreeRow WhiteBalance::getActiveMethod ()
 
 void WhiteBalance::WBChanged(double temperature, double greenVal)
 {
-    GThreadLock lock;
-    disableListener();
-    setEnabled(true);
-    temp->setValue(temperature);
-    green->setValue(greenVal);
-    temp->setDefault(temperature);
-    green->setDefault(greenVal);
-    enableListener();
+    struct Data {
+        WhiteBalance* self;
+        double temperature;
+        double green_val;
+    };
+
+    const auto func = [](gpointer data) -> gboolean {
+        WhiteBalance* const self = static_cast<WhiteBalance*>(static_cast<Data*>(data)->self);
+        const double temperature = static_cast<Data*>(data)->temperature;
+        const double green_val = static_cast<Data*>(data)->green_val;
+        delete static_cast<Data*>(data);
+
+        self->disableListener();
+        self->setEnabled(true);
+        self->temp->setValue(temperature);
+        self->green->setValue(green_val);
+        self->temp->setDefault(temperature);
+        self->green->setDefault(green_val);
+        self->enableListener();
+
+        return FALSE;
+    };
+
+    idle_register.add(func, new Data{this, temperature, greenVal});
 }

rtgui/whitebalance.h

@@ -77,6 +77,9 @@ protected:
     int custom_temp;
     double custom_green;
     double custom_equal;
+
+    IdleRegister idle_register;
+
     void cache_customWB    (int temp, double green); //cache custom WB setting to allow its recall
     void cache_customTemp  (int temp);               //cache Temperature only to allow its recall
     void cache_customGreen (double green);           //cache Green only to allow its recall
@@ -92,7 +95,7 @@ protected:
 public:
 
     WhiteBalance ();
-    ~WhiteBalance () {};
+    ~WhiteBalance ();
 
     static void init    ();
     static void cleanup ();