Add click handler for TGraph

If custom click handler assigned, it will be informed

Resolves https://root-forum.cern.ch/t/64744

Author: linev

modules/hist2d/TGraphPainter.mjs

@@ -1,6 +1,6 @@
 import { gStyle, BIT, settings, create, createHistogram, setHistogramTitle, isFunc, isStr,
          clTPaveStats, clTCutG, clTH1F, clTH2F, clTF1, clTF2, clTPad, kNoZoom, kNoStats } from '../core.mjs';
-import { select as d3_select } from '../d3.mjs';
+import { select as d3_select, pointer as d3_pointer } from '../d3.mjs';
 import { DrawOptions, buildSvgCurve, makeTranslate, addHighlightStyle } from '../base/BasePainter.mjs';
 import { ObjectPainter, kAxisNormal } from '../base/ObjectPainter.mjs';
 import { FunctionsHandler } from './THistPainter.mjs';
@@ -1513,7 +1513,7 @@ class TGraphPainter extends ObjectPainter {
    }
 
    /** @summary Complete moving */
-   moveEnd(not_changed) {
+   moveEnd(not_changed, evnt) {
       const graph = this.getGraph(), last = graph?.fNpoints - 1;
       let exec = '';
 
@@ -1543,6 +1543,17 @@ class TGraphPainter extends ObjectPainter {
             else
                this.drawGraph();
          }
+      } else if (not_changed) {
+         const fp = this.getFramePainter(),
+               m = d3_pointer(evnt, fp.getFrameSvg().node()),
+               fw = fp.getFrameWidth(), fh = fp.getFrameHeight(),
+               valid_x = (m[0] >= 0) && (m[0] <= fw),
+               valid_y = (m[1] >= 0) && (m[1] <= fh);
+         if (valid_x && valid_y) {
+            evnt.preventDefault();
+            evnt.stopPropagation();
+            fp.processFrameClick({ x: m[0], y: m[1] });
+         }
       } else {
          changeBin(this.#move_bin);
          this.#move_binindx = undefined;