WM: add gesture variable to detect first execution

Needed for circle select to replace the current selection.

source/blender/windowmanager/WM_types.h

@@ -427,6 +427,8 @@ typedef struct wmGesture {
 	/* For modal operators which may be running idle, waiting for an event to activate the gesture.
 	 * Typically this is set when the user is click-dragging the gesture (border and circle select for eg). */
 	uint is_active : 1;
+	/* Previous value of is-active (use to detect first run & edge cases). */
+	uint is_active_prev : 1;
 	/* Use for gestures that support both immediate or delayed activation. */
 	uint wait_for_input : 1;
 

source/blender/windowmanager/intern/wm_gesture_ops.c

@@ -251,6 +251,7 @@ int WM_gesture_box_modal(bContext *C, wmOperator *op, const wmEvent *event)
 	}
 #endif
 
+	gesture->is_active_prev = gesture->is_active;
 	return OPERATOR_RUNNING_MODAL;
 }
 
@@ -383,8 +384,8 @@ int WM_gesture_circle_modal(bContext *C, wmOperator *op, const wmEvent *event)
 				}
 				else {
 					/* apply first click */
-					gesture_circle_apply(C, op);
 					gesture->is_active = true;
+					gesture_circle_apply(C, op);
 					wm_gesture_tag_redraw(C);
 				}
 				break;
@@ -422,7 +423,7 @@ int WM_gesture_circle_modal(bContext *C, wmOperator *op, const wmEvent *event)
 	}
 #endif
 
-
+	gesture->is_active_prev = gesture->is_active;
 	return OPERATOR_RUNNING_MODAL;
 }
 
@@ -655,6 +656,8 @@ int WM_gesture_lasso_modal(bContext *C, wmOperator *op, const wmEvent *event)
 			gesture_modal_end(C, op);
 			return OPERATOR_CANCELLED;
 	}
+
+	gesture->is_active_prev = gesture->is_active;
 	return OPERATOR_RUNNING_MODAL;
 }
 
@@ -841,6 +844,7 @@ int WM_gesture_straightline_modal(bContext *C, wmOperator *op, const wmEvent *ev
 		}
 	}
 
+	gesture->is_active_prev = gesture->is_active;
 	return OPERATOR_RUNNING_MODAL;
 }