resources - WPF StaticResource vs DynamicResource -

i have xaml below

<window.resources>     <solidcolorbrush x:key="brushme" color="red"/>     <solidcolorbrush x:key="freezebrushme" po:freeze="true"  color="yellow"/> </window.resources> <stackpanel>             <button background="{staticresource brushme}">static</button>     <button background="{dynamicresource brushme}">dynamic</button>     <button click="button_click">changecolorproperty</button>     <button click="button1_click">changebrushobject</button>     <!--<button background="{staticresource notexistresource}" click="button_click_1">generateresourceforstatic</button>-->     <button background="{dynamicresource notexistresource}" click="button_click_1">generateresourcefordynamic</button>     <button background="green" click="button_click_1">fixedbrush</button>     <button background="{staticresource freezebrushme}">freezebrushstatic</button>     <button background="{dynamicresource freezebrushme}">freezebrushdynamic</button>     <button click="button_click_2">changefreezecolorproperty</button>     <button click="button_click_3">changefreezebrushobject</button> </stackpanel> 

in code behind, looks like

    private void button_click(object sender, routedeventargs e)     {         solidcolorbrush brush = (solidcolorbrush)this.findresource("brushme");         brush.color = colors.blue;         this.resources["brushme"] = brush;     }      private void button1_click(object sender, eventargs e)     {         solidcolorbrush newbrush = new solidcolorbrush(colors.yellow);         this.resources["brushme"] = newbrush;     }      private void button_click_1(object sender, routedeventargs e)     {         this.resources.add("notexistresource", new solidcolorbrush(colors.green));     }      private void button_click_2(object sender, routedeventargs e)     {         solidcolorbrush brush = (solidcolorbrush)this.findresource("freezebrushme");         brush.color = colors.blue;         this.resources["freezebrushme"] = brush;     }      private void button_click_3(object sender, routedeventargs e)     {         solidcolorbrush newbrush = new solidcolorbrush(colors.red);         this.resources["freezebrushme"] = newbrush;     } 

my question if click changebrushobject button first, change dynamic button yellow, click changecolorproperty button, change dynamic button blue, , not affecting static button.

however, if click changecolorproperty button on own, change both static , dynamic buttons blue.

why behaves this? wpf doesn't throw warnings when trying assign new object resource has been referenced static resource control?

i tested non-existing resource referenced dynamic resource. expected, if staticresource references non-existing resource, xaml complain @ compile time , dynamicresource not. however, if click generateresourcefordynamic button, shows green color background, fades away, , reappears again, , repeats. why happens this?

edit: added freeze resource, strange behaviour again. if click changefreezecolorproperty button, through exception. , if click changefreezebrushobject alone, change freezebrushdynamic button color. if click changefreezebrushobject , click changefreezecolorproperty, no exception thrown.

i think making resource freeze make properties of object linked resource readonly. why when changing property, through exception complaining readonly state. freeze doesn't stop changing object itself.