Update TGLabel.cxx

Author: ferdymercury

gui/gui/src/TGLabel.cxx

@@ -80,7 +80,8 @@ TGLabel::TGLabel(const TGWindow *p, TGString *text, GContext_t norm,
    wattr.fMask = kWAWinGravity | kWABitGravity;
    wattr.fBitGravity = 5; // center
    wattr.fWinGravity = 1;
-   gVirtualX->ChangeWindowAttributes(fId, &wattr);
+   if (gVirtualX)
+      gVirtualX->ChangeWindowAttributes(fId, &wattr);
 
    Resize();
    SetWindowName();
@@ -121,7 +122,8 @@ TGLabel::TGLabel(const TGWindow *p, const char *text, GContext_t norm,
    wattr.fMask = kWAWinGravity | kWABitGravity;
    wattr.fBitGravity = 5; // center
    wattr.fWinGravity = 1;
-   gVirtualX->ChangeWindowAttributes(fId, &wattr);
+   if (gVirtualX)
+      gVirtualX->ChangeWindowAttributes(fId, &wattr);
 
    Resize();
    SetWindowName();
@@ -257,7 +259,7 @@ void TGLabel::DoRedraw()
             DrawText(fNormGC, x, y);
             break;
       }
-   } else { // disabled
+   } else if (gVirtualX) { // disabled
       FontH_t fontH;
 
       if (GetDefaultFontStruct() != fFont->GetFontStruct()) {
@@ -438,7 +440,8 @@ void TGLabel::SetTextJustify(Int_t mode)
          break;
    }
 
-   gVirtualX->ChangeWindowAttributes(fId, &wattr);
+   if (gVirtualX)
+      gVirtualX->ChangeWindowAttributes(fId, &wattr);
 
    Layout();
 }